519 



EXTOMOSTOMATA. 



ENTOMOSTOMATA. 



550 



which he also gives three; of the latter Lamarck records four. 

 The number of species of Cerithia at present described exceed 

 one hundred. 



Adanson, speaking of the habits of one of the species of Cei-ithium, 

 says that it lives in the sand amongst grass and mangroves, feeding 

 on ' scolopendres ' and other small marine worms. The individual 

 which formed one of the subjects of the investigation by Mr. Berkeley 

 and Mr. Hoffman, and which was brought from Calcutta, though 

 placed in fresh sea-water, the utmost care being taken to renew it fre- 

 quently, and though all kinds of marine substances were supplied to 

 the animal for food, refused all nourishment, contenting itself with 

 simply walking over the substances, and, in so doing, touching them 

 with its proboscis. As it would not feed, this individual was killed by 

 immersion in spirit. The other specimen, which was anatomised by 

 the zoologists above mentioned, was brought from Ceylon. Dr. J. E. 

 Gray (March 25, 1834) read a note to the Zoological Society of London, 

 giving an account of the arrival in England of two living specimens of 

 Cerithium armatum, which had been obtained at the Mauritius, and 

 had been brought thence in a dry state. That the inhabitants of 

 land-shells will remain alive without moisture for many months is, 

 he remarked, well known. [BuLiNus.] He had had occasion to 

 observe that various marine Molliuca will retain life in a state of tor- 

 pidity for a considerable time ; some facts, in illustration of which, he 

 had communicated to the Society. ('Zool. Proc.,' part i. p. 116.) The 

 present instance included however a torpidity of so long a continu- 

 ance as to induce him to mention it particularly. The animal, 

 though deeply contracted within the shell, was apparently healthy, 

 and beautifully coloured. It emitted a considerable quantity of bright 

 green fluid, which stained paper of a grass-green colour ; it also coloured 

 two or three ounces of pure water. This green solution, after stand- 

 ing twelve hours in a stoppered bottle, became purplish at the upper 

 part ; but the paper retained its green colour though exposed to the 

 atmosphere. A specimen of C. Teleicopium, sent from Calcutta to Mr. 

 O. B. Sowerby in sea-water, lived out of water in a small tin box for 

 more than a week. Cerithium has been found in the sea on various 

 bottoms, and in actuaries at a depth ranging from the surface to 

 seventeen fathoms. 



Foail Cerithia. Deshayes, in his tables, gives the number of fossil 

 (tertiary) Cerithia at 220, and of these he records C. rulgatum, C. 

 LatreiUii, C. doliolum, (J. giganieum, C. alucaita; C. granuloeum, and 

 C. bicinctiim, as both living and fossil. He gives two fossil (tertiary) 

 species of Pirena and two of Triforit. The form is found from the 

 Supracretaceoua to the Oolitic group, both inclusive. Potamide is 

 recorded in the Weald-Clay, Sussex (Mant.); and Nerinea, in the 

 Oolitic group (Bailly) near Auxerre, St. Mehiel (Meuse), Kimmeridge 

 Clay, Coral Rag, Bernese Jura, Forest Marble, Oxford Oolite, Dorset 

 (Nerinea Goodhallii), Inferior Oolite. 



Dr. Lea (' Contributions to Geology ') describes and figures from the 

 Claiborne Beds, in America, a shell which he names provisionally 

 Cerithium (t) ttriatum; observing that he is by no means satisfied in 

 placing this shell among the Cerithia. It has a stronger resemblance in 

 the mouth to the genus Melania, but being a marine shell, cannot, he 

 remarks, with propriety be placed in that genus. De Blainville, he adds, 

 figures a shell (' Malacologie," pi. 21, bis, fig. 2), under the name of 

 Potamidei frayilia, which certainly ought to belong to the same genus 

 with this, the mouth being very nearly the same. Until more species 

 shall be obtained, Dr. Lea has forborne to create for it a new genus. 

 He further states that there have been no Cerithia yet found in the 

 beds at Claiborne, although they abound in England and on the Con- 

 tinent in the Tertiary Formation, there being 137 species in the Paris 

 Basin alone. Woodward states that the fossil species exceed 460 in 

 number. 



Stelanoptu. Animal furnished with a proboscidifonn muzzle, with 

 two contractile, conical, annulated tentacula, having each at their 

 external base an oculated peduncle ; foot attached to the neck ; res- 

 piratory orifice in the canal formed by the union of the mantle with 

 the body. Shell with an epidermis, elongated, fusiform, or conico- 

 cylindrical, with a pointed summit ; whorls of the spire from 6 to 

 15, the last often forming two-thirds of the shell; aperture oval, 

 oblong ; columella solid, callous, truncated at its base, separated 

 from the anterior border by a sinus, the callosity prolonged upon the 

 convexity of the penultimate whorl, forming a canal backwards ; 

 sometimes a sinus at the posterior part of the right border. 

 Operculum horny, subspiral. 



' The genus in rather -fluviatile than marine, contrary to Cerithium, 

 according to De Blainville. Lamarck, who gives but two species, M. 

 c'jstata and M. Itrviyata, speaks of them decidedly as fluviatile. Kang 

 ays that the genus was established by M. de Fdrussac for fresh- water 

 shells, whose callous and truncated columella did not permit their 

 arrangement with Melania. The latter, in his Monograph, divides 

 them into two groups, the first consisting of those species which have 

 a single sinus at the border of the aperture, separating it from the 

 columella (Melanopni, Lam. ; M. buccinoidea) ; the second consisting 

 of those species which have two distinct sinuses at the external 

 border of the aperture, one which separates it from the columella, the 

 other situated near the union of this border with the penultimate 

 whorl. (Pirena, Lam.) De Blainville gives the following division of 

 the genus : 



o. Subturriculated Species. 

 Ex. M. costata. 

 Locality, Syria, in the Orontes. (Lamarck.) 



Melanopsis costata, 

 ft Oval Specie?. 



Ex. M. buccinoidea. 



y. Convex Species (Espcees Roufle'es). 



Ex. M, Souei. [MELANOPSIS.] 



The genus Melania is related to Melanopsis, and is sometimes 

 included with Paludomui in the family Melaniada. [MELANIA.] 



Planaxis. Animal unknown. Shell oval, conical, solid, trans- 

 versely furrowed ; aperture oblong ; columella flattened and truncated 

 anteriorly, separated from the right border or lip by a sinus ; right 

 lip furrowed or rayed within, and thickened 'by a decurreut callosity 

 at its origin. Operculum horny, oval, delicate, subspiral. 



Lamarck established this genus for certain small shells approxi- 

 mating closely to the Phaaianellte, but differing from them by the 

 truncation of the anterior part of the columella. He only records 

 two species, namely P. swlcata and P. undulata. M. Rang states 

 that he possesses six well-distinguished species. Woodward, in his 

 ' Manual of the Mollusca," gives eleven species. They are found in 

 the West Indies, Red Sea, Bourbon, India, the Pacific, and Peru. 



The Planaxis is a littoral shell, and is sometimes found under stones. 

 M. Rang says that he had had occasion to observe the animal at the 

 Isle of France (Mauritius), where the rocks are sometimes covered 

 with them, but, having lost his notes, he is unable to give its 

 principal characters. According to his recollection, the animal differed 

 very little from that of PhatianeUa. M. Deshayes, in his Tables, puts 

 the living species at four. 



Ex. P. tulcala. 



Planaxis sulcata. 



Deshayes, in his Tables, gives five species as fossil in the Tertiary 

 strata. 



Svlula. Animal spiral, very much elevated ; foot very short and 



Shell of <i'if maculata, and last whorl of the shell with the animal and 

 opercultm a. 



