Body provided with a large proboscidiform exsertile sucker, with a bunch (grappe) of ovaries at its base, lodged in a large single excavation of a natatory anterior cordiform organ, receiving also the posterior, which is also cordiform and hollowed into a cavity with a posterior and suboval orifice. Example, Cucubalus cordiformis, the only species cited of the genus established by MM. Quoy and Gaimard. diversiform productions. Mouth proboscidiform, at the extremity of Length, two lines. Differs from the a sort of vesicular stomach. Example, Protomedea lutea. other Diphyde, first, in having the nucleus much less hidden and sunk in the anterior natatory body, which has moreover only one large cavity in which it is plunged; secondly, in Generic Character.-Body short, cylindrical, fleshy, swollen above having the oviferous production very short; and, lastly, in the mode 8. Rhodophysa. Rhodophysa Helianthus. into an aëriferous bladder, and provided below with a variable number of gelatinous bodies, which are full, costiform, forming a single Example, Cymba sagittata (Quoy and Gaimard); Nacelle sagittata penetrating into the anterior organ, and provided with a round (De Blainville). Locality, Straits of Gibraltar. terminal aperture. Example, Calpe pentagona (Quoy and Gaimard). Locality, Straits of Gibraltar? 16 Cymba sagittata. M. de Blainville remarks that he ought to observe that M. Eschscholtz says that this genus, to which he unites the two following genera, possesses an anterior natatory organ with two cavities, and of these the natatory cavity projects in the form of a tube. M. de Blainville further observes that this genus does not differ from the Cuculli, except in the form of the natatory organs; in fact, the disposition of the nucleus in the bottom of the single cavity into which the anterior organ is hollowed, and the penetration of the posterior organ into this same cavity are absolutely the same as in the two preceding genera, as M. de Blainville has been able to satisfy himself from the examination of many individuals preserved in spirit. Amphiroa alata. 1, 1 a, Amphiroa alata; 1 b, its nucleus extracted. 16 with a single rounded aperture communicating with a single deep membranes, truncated at the two extremities, with a posterior apercavity, towards the end of which is a granular corpuscle. Example, Pyramis tetragona (Otto). ture, with appendicular lobes on its circumference, and leading into a very long and blind cavity. Example, Sulculeolaria quadrivalvis (Lesueur). Locality, Mediter ranean (Nice). 16 Diphyes Borg. Body gelatinous, rather firm, perfectly regular, symmetrical, subpolygonal or oval, compressed on the sides and furnished with two lateral rows of extremely fine cirrhi. A large posterior aperture pierced in a sort of diaphragm with appendicular lobes, binary above, leading into a large 1, the entire animal (profile); 1 a, anterior part of the same; 1 b, posterior cavity with muscular walls. An ovary part; 1 c, animal magnified; 1 d, posterior part of the same. M. Eschscholtz makes this organised body a species of his genus Eudoxia, which comprehends Cucubalus and Cucullus of Quoy and Gaimard, admitting that the two natatory organs are intimately united so as to form, apparently, but one. at the anterior superior surface, Example, Galeolaria australis, Beroïdes 6. Rosacea. Galeolaria australis. Body free, gelatinous, very soft, transparent, suborbicular, with a single terminal aperture at one of the poles leading into an oval cavity which communicates with a depression, whence proceeds a cirrhigerous and oviferous production. Example, Rosacea Ceutensis (Quoy and Gaimard). Rosacea Ceutensis. 7. Noctiluca. Body free, gelatinous, transparent, spheroïdal, reniform, with a sort of infundibuliform cavity, whence proceeds a proboscidiform contractile production. Example, Noctiluca miliaris (Lamarck). M. Surriray, a doctor of medicine, while investigating the cause of the phosphorescence of the sea-water at Hâvre, appears to have been the first who observed and called attention to the genus Noctiluca, which he described and figured in the memoir that he communicated to the class of sciences of the French Institute. Its size hardly equals that of a small pin's head, and it is as transparent as crystal; he found it very common in the basins at Hâvre, sometimes in such abundance as to form a considerably thick crust (croûte assez épaisse) on the Noctiluca miliaris. surface of the water. It has also been observed in England as the and Gregarinada conduct us towards the lowest plants. These relacause of phosphorescence in the ocean. tions may be thus represented : 8. Doliolum. Body gelatinous, hyaline, cylindrical, truncated, and equally attenuated at the two extremities, which are largely opened and without apparent organs. Example, Doliolum Mediterraneum (Otto). M. Otto describes the organism on which he has established this genus as swimming by ejecting and absorbing the water by means of the alternate dilatation and contraction of its two orifices. M. Delle Chiaje (Mem.,' tom. iii.) seems inclined to believe that the Doliolum of Otto is merely a fragment of a species of Holothuria, which he names Holothuria inhærens. De Blainville observes that if Otto's description of the motion, &c., above stated, be correct, it is probable that the animal is a true Biphore. Among the genera," says De Blainville, “incertæ sedis, which, wrong or right, have been connected with Physsophora or Diphyes, without even being very certain that they are animals, we shall cite the following genera intentionally omitted in our work." Cupulites (Quoy and Gaimard), placed among the Physsophora, whose capsules are disposed on each side of a very long axis, established on an organised body, figured pl. 87, fig. 4-16 in the zoological part of the 'Voyage of the Uranie.' Not having met with this animal in their second voyage, MM. Quoy and Gaimard doubt (Astrolabe, Zoolog.,' t. iv. p. 53 n.) whether it is an incomplete Physsophora or a Stéphomonise (Stephanomia?) with hollow natatory organs. Cuvier places the genus between Hippopus and Polytoma (Quoy and Gaimard, 'Zool. of the Uranie,' pl. 87, fig. 12, 13), which may be defined to be an oval mass of globular trivalvular corpuscles (corpuscules globuleux comme trivalves), and which MM. Quoy and Gaimard conceive to be rather a Biphore than a Physograde. Racemis. Tetragona (p. 10), (Quoy and Gaimard, Zool. of the Uranie,' pl. 86, fig. 11). This the authors themselves ('Astrolabe,' iv. p. 103) have recognised as being nothing more than the posterior point of Diphyes hispida. Racemis (Delle Chiaje, Cuvier), figured by Delle Chiaje, 'Mem.' tab. 50, f. 11, 12, and described as a globose vesicle endowed with a very quick motion, and disposed towards an ovate shape; but, observes De Blainville, the figures and description are too incomplete to afford a supposition of what it is; in fact, Delle Chiaje confines himself to stating that his Racemis ovata executes all the rotatory and rapid motions at the surface of the water, and that those of each vesicle are so lively that it has been absolutely impossible to perceive the aperture with which, according to Delle Chiaje, they are provided. Cuvier only adds to the description of Delle Chiaje, who also places Racemis near the Physsophora, a small membrane with which each vesicle is furnished. M. De Blainville concludes by observing that he had seen a drawing, by M. Laurillard, which had been taken at Nice from one of these organised bodies while alive, and that he supposed that it might well be a mass of eggs of Mollusca. Relations of the Acalephe to the other Invertebrata.-Mr. Huxley, in his memoir before referred to, proposes to consider the Acalephæ in some new relations. The presence of stinging hairs in these animals, in common with the Hydroid, Sertularian, and Anthozoic Polypes, he regards as a fact of primary importance. He endeavours to show that this fact, combined with the radiate polype form, and the composition of the body of two distinct membranes, forms a very good positive character for a group embracing the Hydroid and Anthozoic Polypes, and the Acalepha. He proposes to give the name of Nematophora (thread-bearers') to this group, in allusion to the characteristic presence of the 'thread-cell.' Frey and Leuckart had, however, applied the term Cælenterata to the same group. It will admit of subdivision into two equivalent subclasses: one including the Hydroid Polypes, the Diphyde, Physsophorida, and Medusida, in which the stomach is not distinct from the common parietes, and the reproductive organs are external; the other, embracing the Anthozoic Polypes and Beroïde in which the stomach is distinct from the common parietes, and the reproductive organs are internal. The author proposes the terms Anacioa and Ecioa for these two divisions. These groups mutually represent each other as follows: those of Horses' Feet,' December, 1836, in which he noticed those in Mr. Babbage, in his paper 'On Impressions in Sandstone resembling the channel of a stream on the extensive moor called Pwll-y-Duon, about seven miles from Merthyr Tydvil, to which his attention was drawn by Mr. Guest of Dowlais, and the analogous casts in the old red-sandstone of Forfarshire, there called Kelpies' Feet, described some observations made by Sir C. Lyell, on impressions left by Medusa on the rippled sand near Dundee. On removing the gelatibut having around half the border a depression of a horse-shoe form. nous body of the animal, a circular space was exposed, not rippled, These marks, however, were not considered by Sir C. Lyell as identical invite further observations, and to make it desirable to possess with those called Kelpies' Feet, but merely so far analogous as to drawings of the impressions which different species of Medusa leave when thrown by the tide upon a beach of soft mud or sand. (Geol. Proc.,' vol. ii.) [See SUPPLEMENT.] lous division of Dicotyledons. Its type is the genus Acanthus. The ACANTHA'CEÆ, an order of plants belonging to the Monopetaspecies are herbaceous or shrubby; they are extremely common in every tropical country. Many of the species are mere weeds; others bear handsome flowers with gaudy colours, but seldom with any medicinally as emollients or diuretics. odour; a very small number have been occasionally employed The roots of Acanthaceae are either annual or perennial. The nearly round; their inside is occupied by a large proportion of pith, stems are usually four-cornered when young, but afterwards become Analysis of Acanthacea. 3 which is enclosed in a thin layer of imperfectly formed wood; and at each joint there is a slight tumour with an articulation, by which they are readily known from both Scrophulariacea and Verbenaceœ. Their flowers are often enclosed within large, leafy, imbricated bracts (1). The calyx (2) is usually composed of either four or five parts, which overlap each other, and occasionally grow together at the base. The corolla (3) is monopetalous and irregular. The stamens (4) are either two or four, but in the latter case are of unequal lengths. The pistillum (6) is superior and turcilled. The seed-vessel (5) contains two cells, which burst when ripe, often with elasticity, and expose a few roundish seeds hanging to the cells by curious-hooked processes. The stems of all the species emit roots very readily from their tumid articulations; on which account gardeners universally increase them by cuttings of the full-grown branches. They are always easy to cultivate, provided they are not kept in too cold or too dry a situation. The annual kinds freely produce seeds, by which they are readily multiplied. The most common genera are Justicia, Acanthus, Ruellia, Thunbergia, Barleria, Eranthemum, Lankesteria, and Henfreya. (Brown's Prodromus Flora Nova Hollandia; Bartling's Ordines, Naturales; Lindley's Introduction to the Natural System; and Nees von Esenbeck's Exposition, in the third volume of Dr. Wallich's Planta Asiatica Rariores.) ACA'NTHION, in Zoology, a genus of Rodentia, established by M. F. Cuvier, and embracing two species, which are only known, at present, by their osteology. In the number and form of their teeth, |