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themselves. Thinking, from my limited means of examination, and from its being associated with Heterostegina, that this fossil must be considered one of the same genus, I gave it the above specific designation, but having lately cut away a little of its surface to examine its internal structure I find that it is distinctly a Cycloclypeus.

The cells of this specimen diminish in size towards the centre and become almost globular; but this may be, because the central cell happened to be minute instead of large. In Dr. Carpenter's typical form however, the cells are deeper in the centre and become shallower outwards, and if this be always the case, then C. mammillatus follows what I have considered to be the normal form of the horizontal planes in Orbitoides dispansa and Orbit sides Mantelli, especially when commencing with a minute cell; rather than typical Cycloclypeus, which, contrary to all the other foraminifera, appears to begin in the centre with large chambers, which go on decreasing in size outwards, without first going down to the smaller size of their situation, and then increasing again towards the circumference. But for this, and the chambers exchanging their quadrangular for a globular form towards the centre, together with the smallness of the fossil, there is no difference that I can see between the fossil Cycloclypeus of the S. E. coast of Arabia and the recent one described by Dr. Carpenter (Phil. Trans. pl. xxx. fig. 1).

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Orbicu'ina Malabarica, Cart.—This fossil, which I had described under the name of Orbitolites Malabarica,(Ann. v. II. p. 425, 1855,) I found afterwards to be an Orbiculina, from its resemblance to Orbiculina angulata, Lam. (Encyl. Méthod. t. iii. pl. 468, fig. 3), and I therefore made this correction in the vth vol. of the Journal of the Bombay Asiatic Society, p. 631; immediately after which, that is to say before the sheet had passed through the press in which my correction was printed, I had the pleasure to receive, through Dr. Carpenter's kindness, his second "Memoir” on the Foramiuifera, in which I found that he had also made the same correction. I mention this chiefly to point out the great resemblance between the figure in the Encyclop. Méthod. to which I have alluded, and Orbiculina Malabarica. For a description and illustration of the fossil itself, see " Ann.” loc. cit.

Variety a.
Largest size.—Breadth 4 inch.

Loc.-Khattyawar, on the coast near Poorbunder, in yellow compact limestone, Capt. Constable, H.M.I.N.

Associates.-- Fossils of the Middle Tertiary Epoch like those accompanying O. Malabarica, (typical form).

Obs. The only differences between this fossil and the typical form are, that the chambers are much smaller in the specimens from Khattyawar; the structure appears to be finer, and from being in a purer, more compact, and fawn-coloured limestone, which is densely charged with them, they appear from their light colour and fine structure identical with Orbitolites complanata ; but the distinct spiral arrangement in the centre, which is very evident under even a strong magnifying lens, establishes the difference directly.

ORBITOLITES, Lam. Cyclolina pedunculata, Cart. (Ann. p. 176.)—Since I have had the advantage of Dr. Carpenter's clear and valuable exposition of the structure of Orbitolites (Phil. Trans. 1855), there is no longer any doubt of my false identification of this fossil with d'Orbigny's Cyclolina, nor of the true one being with Orbitolites ; and therefore, if it be really a new species, which I also doubt very much, it might now go by the name of “ Orbitolites pedunculata.I expect, after all, it will be found to differ very little from Orbitolites complanata of the “ Paris Basin."

Associates.-Alveolina elliptica, and a small nummulite belonging to the “Striata," on the Buran River in Lower Sind; and on the same river with the Orbitolina beforementioned, “ No. 3.” With Alveolina spheroidea and Operculina in the white limestone forming the summits of the great cliff-scarps behind Morebat ; and also with Orbitolina, “No. 1antè, in broken masses under the great promontory of Ras Sajar, on the S. E. coast of Arabia.

Internal structure of Orbitolites pedunculata.—This is the same as that given by Dr. Carpenter in his vertical sections 8 and 9, pl. vi., and in his horizontal surface-view, fig. 8, pl. vii. The chambers in the centre have not run into each other vertically, as shown in Dr. Carpenter's “ideal representation,” fig. 6, pl. v., neither are the chambers of the surface oblong but globular, while in the centre the rows are frequently oval instead of circular. Both these differences, however, as Dr. Carpenter observes, are worth no more than marks of variety.

The peduncle at the base in the centre is composed of amorphous shell-substance, through which a number of branched transparent lines extend upwards into the centre of the disk, indicative of their once having been canals, perhaps occupied by sarcode. Dr. Carpenter

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observes, that the fossil was probably attached during its lifetime to some marine body, and therefore the peduncle here may be of very little specific value ; thus reducing the species to Orbitolites complanata.

"Cyclolina Arabica, Cart.” (Geol. Pap. Western India, p550).This, if it be a new species, should have its name changed to " Orbitolitęs Arabica.The only difference between it and the Sind orbitolite, is its larger size and finer structure, which are by themselves worth nothing as specific distinetions; hence, perhaps, this also had better be considered as a variety of 0. complanata.

Associates. They have been given above under C. pedunculata.

Note.- Feeling satisfied now that these fossils are Orbitolites, and not Cyclolina, d’Orb., and that I have not found Orbitolitesin the Cretacean Strata of the South-East coast of Arabia, I have first to correct my errors in nomenclature to accord with this conclusion, which has been done above; and next my inferences, which were based on the assumption that this Orbitolites was identical with d'Orbigny's Cyclolina.

My inference (Geol. Pap. W. I., p. 627,) that the white limestone forming the summit of the great cliff-scarps on the S. E. coast of Arabia was of Cretacean Age, because it contained a discoid fossil identical in appearance with Cyclolina cretacea, d’Orb. (this fossil, according to d'Orbigny, being confined to the Cretacean Period), is perceived to be wrong, since it is now proved to be Orbitolites, which brings back the summit-portion of these scarps to Eocene Age, as assumed in the first edition of my "Memoir" on the Geology of this coast (Jour. Bomb. Asiat. Soc. v. iv., p. 95), wherein the fossil itself was also first called “ Orbitolites."

Again, at p. 701, foot-note, the mistaking of this Orbitolites for Cyclolina has led to a similar error ;-for, finding the Sind orbitolite associated with fossils of the Eocene Period in that country, and considering it also a Cyclolina, I inferred that d'Orbigny himself was wrong in restricting the existence of this fossil to the Cretacean Period; whereas, now that it is known to be an orbitolite, the inference is in the opposite direction, and in support of d'Orbigny's assertion.

What then is d'Orbigny's Cyclolina? A question which may be first met by stating, that "had d'Orbigny made plain what Cyclolina is, there would have been no occasion for such a question.".

From what Dr. Carpenter has stated, it is evident that he was inclined to view Cyclolina as a species of Orbitolites, (1st Mem. p. 226, pl. vii., fig. 14); while Messrs. Parker and Jones, (Ann. v, vi, p. 36

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1860), consider it an "excessively out-spread” form of Orbitolina, “ "judging from d'Orbigny's description and figures,” in his Foram. Foss. de Vien. p. 139, pl. xxi, figs. 22–25.

In the latter view I acquiesce now, and even applied the name of Cyclolinato one of these out-spread forms of Orbitolina which I found in the great deposit of Orbitolinæ on the S. E. coast of Arabia (Geol. Pap. W. I., p. 549), from its resemblance to d'Orbigny's figures, but wrongly identified it with the “discoid fossil,” of the scarp 2,000 feet above, now seen to be Orbitolites ;—the former in company with Cretacean, and the latter among a type of Eocene fossils.

All this confusion has arisen from the imperfect way in which d'Orbigny has described and figured his Cyclolina cretacea. It would have been better if he had never written anything about it, than just enough to mislead.

He states that it is "æquilateral.” This is a character of Orbitolites and not of Orbitolina. That the chambers are concentric, “making each a complete circle round the others of the same form ;" by which I understand him to mean an annular chamber without septa, in fact a hollow ring. But so far as my observation goes, the concentric ring. spaces of Orbitolina, if not divided up into chambers like those of 0. lenticularis, should interdigitate with each other as in Patellina corrugata (Ray Soc. Pub., Monograph by Prof. Williamson, p. 46, pl. 3,

p figs. 86-89). This annular form however, according to d'Orbigny, is the peculiar characteristic of his Cyclolina, viz. "circular chambers."

Again, as regards d'Orbigny's figures (loc. cit.), nothing can be more like the expanded, flattened disk of Orbitolina lenticularis than his horizontal view of Cyclolina (fig. 22). It has also, according to the shading, an elevated centre, but which does not appear in the lateral view (fig. 23). Again, if it were like Orbitolina lenticularis, the margin should be rounded and thin, for that of the latter fossil is thin and everted ; instead of which it is flat, and, if anything, thickened, for it obscures the rest of the fossil when viewed edgewise,- if d'Orbigny's figure 23 be correct. If equilateral, it should have the same annular markings on each side. How then can it be an "excessively outspread” form of Orbitolina annularis, as assumed by Messrs. Parker and Jones? It is needless to conjecture further, for until the fossil is better illustrated and more satisfactorily described, we shall never know what it is. The peculiarity of “annular chambers" and the discrepancy in d'Orbigny's figs. 22 and 23, where the former represents an elevated centre and the latter does not show it edgewise, while there is nothing in the short, meagre description accompanying it to show that the disk was excavated, renders the record almost worse than useless, and shows that, when anything is described, it should be done so satisfactorily, or a statement made to the effect that the data were not sufficient for this purpose.

Résumé.

From the foregoing observations on structure then, we may sum up. the description of the discoidal Foraminifera in the following way :-

Test.The test is situated in the substance of the animal, and in Operculina consists of the spiral or horizontal lamina and the marginal cord. The spiral lamina again is divided into the parts which cover the chambers and those which cover the interseptal spaces. The former is pierced with close-set, vertical tubuli, and the latter, with more or less scattered, minute branches of the interseptal canals. Besides this, there are non-tubular spaces or puncta, more or less regularly scattered over the chambers and interseptal spaces, which answer to. the external ends or bases of the conical columns of condensed shell-substance, intended apparently for strengthening the test, and these are accompanied in some species of Nummulites, by a horizontal branchwork of the same material, which gives them very much the appearance of the lacunæ and their canaliculi in bone, yet they present no appearance of channelling, but on the contrary, a heterogeneous composition, as regards size, of small pillars and pellets of condensed shellsubstance, respectively. The marginal cord on the other hand, is composed of spicules, an inter-spicular substance, and canals, which are all more or less arranged in layers radiating from the centre of the base of the cord, which is straight, to its circumference, which is semi-circular. The spicules overlap each other longitudinally, and the canals form a densely reticulated structure throughout the substance of the cord whose branches open in all directions upon its surface. As the test arrives at its full growth, the marginal cord is bent down over the last chamber to meet its preceding turn, to which it becomes attached, and the Operculina thus hermetically sealed. Hence d’Orbigny's original statement, that the test is without an opening like that of the Nautilus and Ammonites, and, without a siphon.

Canal-system.—The canal system consists of,- 1st, two great spiral

nals, one in each horizontal half of the test, which run from its commencement to its termination, and are situated respectively on each side the marginal cord, at its point of junction externally, with the spiral

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