362 MOLLUSCA. 



The external edge of the aperture is crenulated in several species. 



The animal is more highly ornamented, and is generally furnished 



with three or four filaments, on each side, as long as its tentacula. 



The eyes are planted on particular pedicles at the external base of 



the tentacula; the operculum is round and horny. 



A small species, the Trochus tesselatus, L.j Adans., Seneg., 

 XII, 1; List., 642, 33, 34, with a brown shell spotted vyith 

 whitish, is very abundant on the coast of France(l). 



Phasianella, Lam. 



An oblong or pointed shell, similar to that of several Bulimi and 

 Lymnaese; the aperture also higher than it is wide, and furnished 

 with a strong operculum; base of the columella sensibly flattened, 

 but no umbilicus. 



They inhabit the Indian Ocean, and are much sought for by col- 

 lectors on account of the beauty of their colours. The animal is 

 provided with two long tentacula, with eyes placed on two tubercles 

 at their external base, and with double lips that are emarginated and 

 fringed, as well as the wings, each of which has three filaments(2). 



Ampullaria, Lam. 



A round, ventricose shell, with a short spire, as in most of the He- 

 lices; the aperture higher than it is wide, and provided with an oper- 

 culum; the columella umbilicated. 



They inhabit the fresh or brackish Avaters of hot countries. The 

 animal has long tentacula, and eyes placed on pedicles at their base. 

 In the roof of the respiratory cavity, by the side of a branchial comb, 

 according to the observations of Messrs Quoy and Gaymard, is a 

 large pouch, without an issue, that is filled with air, and which may 

 be considered as a natatory bladder(3). 



The LANisTiE, Montf., are Ampullaria?, with a large, spiral, con- 

 voluted umbilicus(4). 



(1) Add: Trochus labeo, Adans., Sencg., XII, Ust, 68, U2;Troch. Fharao- 

 nius, List., 637, 25; Tr. rustlcus, Chemn., V, clxx, 1645, 46, Tr. nigerrimus, 

 lb., 47; Tr. segyptius. Id., clxxi, 1663, 4;Tr. viridulus, lb., 1677; Tr. 

 carneus, lb., 1682; Tr. albidus. Born., XI, 19, 20- Tr. asper, Chemn., lb., 

 clxvi, 1582; Tr. dtrinus, Knorr., Del., I, x, 7;Tr. granatum, Chemn., V, 

 clxx, 1654 55; Tr. crocatus. Born., XII, 11, 12; Turbo atratus, Chemn., V, 

 clxxv'i, 1754 55; Turbo dentatus. Id., clxxviii, 1767, 8, &c. 



(2) Buccinum tritonis, Chemn., IX,cxx, 1035, lQo6; Helix solida. Born., XIII, 

 18, 19. 



(3) Helix ampidlacea,L,., List,, VoO;Bulimus wrccjfs, Brug., List., 125, 25. 



(4) Ampulla carinata, Oliv., Voy. en Turq., pi. xxxi, f. 7, copied Blainv., 

 Malac, xxxiv, 3. 



