131 



PALUDINID.E. 



PALUDINID^E. 



193 



Animal and Shell of Oeratodn fatcialta, Gnildinu ; Ampullaria Cornu- 

 Arirtin, Sowerby. (Guilding.) 1, the animal creeping. 2, the animal in a 

 Mipine position ; a, Operculum ; b, the rijcht siphon ; c, the respiratory siphon. 

 3, head, tratacula, eye* at their base, and cervical aliE. 



faction, quietly creeping about upon the mud. He gave many indi- 

 viduals to M. Deshayes, who kept them alive from four to five months. 

 M. Deshayes relates that it became an object of inquiry how aquatic 

 animals unable to respire, except by means of a pectinated brauchia, 

 could remain alive so long out of the element apparently necessary 

 to their existence. Nearly all the persons, he remarks, who occupied 

 themselves with this phenomenon, thought that the animal on retiring 

 into its shell carried with it a certain quantity of water, which could 

 not escape owing to the retention of the operculum, which closes the 

 aperture with great exactness. Others thought that the humid air 

 carried upon the branchiae was sufficient to keep tip the respiratory 

 action. " Wishing to know," continues M. Deshayea, " whether there 

 were anything in the structure of the animal which could explain the 

 singularity, we soon perceived that the upper wall of the branchial 

 cavity was doubled, and formed a great pouch, the aperture of which 

 was placed backwards, above the origin of the branchiae. Plunged in 

 the water, the animal has this pouch constantly filled with the ambient 

 liquid, and on retiring into its shell and shutting itself up under 

 its operculum, this bag still remains filled with water, and thus 

 furnishes the necessary materials for the function of respiration. 

 Everything leads us to believe that this is the only cause which 

 permits the Ampvllarite, pectinibranchiated aquatic animals, to remain 

 a long time out of the water without perishing, and this explains also 

 how it happens that in certain lakes which are annually dry, Ampul- 

 lariit are always to be found. When the great heats approach and 

 they plunge themselves into tho mud or sand, they preserve in their 



branchial sacs the quantity of water necessary for them during the 

 whole time of drought." 



This is one of those beautiful provisions which meet the naturalist 

 everywhere. The tropical torrent and lake may yield to the dry 

 season and burning sun, but the Ampullaria, secure in the possession 

 of his water-bag, can afford, like the camel in the desert, to wait till 

 the rains furnish a fresh supply, and again fill the parched channel. 



The species are found in the rivers and lakes of warm climates. 

 Species, some of them very large (A. Guyanensil, A. Urceus, and 

 A. Gigai, for example), have been found in Asia, Africa, and America, 

 especially the southern portion of the latter. 



A. globosa, Globose Apple-Snail, or Idol-Shell, is a good example of 

 this genus. There are about 50 recent species of this genus. The 

 following sub-genera have been formed out of it : Pomus, Mania, 

 Asolene, Laniitts, and Meladomts. 



Ampullaria globosa ; the aperture closed by the operculum. 



Ampullaria cfiua of Swainson. Mr. Guilding is of opinion that 

 this species forms the transition through Ceratodes to the PtanorTnda, 

 and that it is probably more allied to that genus than to A mpullaria. 



The genus Ceratodes of the last-named author is characterised as 

 having a simple lip ; a horny operculum ; a discoid shell ; a very large 

 and deep umbilicus, and an evanescent columclla. The sole species 

 given by him is Ceratodes Cornu-Arietii above copied. 



Mr. Swainson thus defines the genus Ampullaria: Shell globose, 

 rarely discoid, turbinate ; spire very short ; aperture oblong, pointed 

 above, rounded below. The same author characterises the four sub- 

 genera as follows : 



Ampullaria (Lamarck). Outer lip thin ; operculum horny. Ex. 

 A.fatciata of Lamarck. 



Pachylabra. Outer lip thickened ; operculum shelly. Ex. P. globosa, 

 Swainson. 



Lanites (Montf). Shell reversed ; the body-whorl ventricose only 

 in the middle ; outer lip generally thin. Ex. L. Quinaiaca. Sowerby's 

 ' Manual,' f. 319. (' Malacology,' 1840.) 



The number of recent species recorded by M. Deshayes in his 

 ' Tables ' is 24 : in the last edition of Lamarck the numbers given 

 are 27, including Ampullaria arellana and A. fragilit, of which we 

 shall presently have occasion to speak more at large. Neither 

 Mr. Swainsou's Ampullaria globosa, Captain King's A. Cumingii, nor 

 Mr. Lea's A. Pealiana appears among these species. Mr. Swainson 

 gives Ildix ampullacea, var., Gmelin, as a synonym of his A. globosa, 

 but the former stands as a synonym for A . fascia/a, Lam., in the last 

 edition of the ' Animaux sans Vertfebres.' Mr. Swainson considers it 

 distinct, and quotes the description and figure of Chemnitz, who, like 

 other authors, considered it a variety of Helix ampullacea. The 

 rivers of India are given as the locality, by Mr. Swainson. 



Some of the A mpullaria, or Apple-Snails, are of large size. 



Ampullacera, Quoy (Amphibola, Schumacher). Animal spiral, 

 globular, convex ; the foot short, quadrilateral, and with a marginal 

 anterior furrow. Head large, flattened, notched into two rounded 

 lobes supporting two sessile eyes, without the appearance of tentacles. 

 Pulmonary cavity limited anteriorly by a collar, and having its aper- 

 ture at the right border. Mouth membranous. Both sexes united. 

 Shell rather thick, globular, ventricose, deeply umbilicated, aperture 

 round or oblique, with the borders united ; spire short, but projecting. 

 Operculum horny, delicate, but little spiral, sometimes with a heel or 

 projection. (Quoy.) 



M. Quoy says of this genus, " We have a mollusc breathing air 

 although it lives in pools, possessing the two sexes united, but being, 

 notwithstanding, an insufficient hermaphrodite. It is apathic, and 

 comes but little out of its shell, into which it retires very far upon tho 

 slightest touch. We found it sunk in the muddy sand, under some 

 inches of saltish water, with its aperture full of earth. It is found in 

 great abundance in New Zealand, where it is largely eaten by the 

 natives." 



M. Deshayes adopts this genus, which he thinks one of the most 

 interesting that has been for a long time discovered. " It offers in 

 fact," says he, "an entirely novel combination of an aquatic animal 

 pulmonated and operculated, and fills up a lacuna. It is, with refer- 

 ence to the aquatic Pulmonata, what the Hdiciiue are with reference 

 to the terrestrial Pulmonata; Ampullacera, iheo, will constitute in 



