48 MOLLUSCA. 



Siphonostomatous are : 



Fam. Cypraeidae, (Cowries). Cyprcea tigris Lam ; O. moncta L. 



Fam. Tritoniidae, (Tritonshorner). Tritonium variegatum Brug. ; Ranella 

 gigantea Lam. 



Fam. Doliidae. Cassu c.ornuta Lam. ; Doliitm galea L., Mediterranean. 



Fam. Strombidse (Alata) (Flugelschnecken). Strombus Isabella Lam. ; 

 Pteroccras lambis Lam. ; Rostellaria rectirostris Lam. 



Fam. Naticidae. Natica auipullaria Lam. ; Slgaretus haliotoideus L., 

 Atlantic. 



Fam. Capulidae, (Miitzenschnecken). Capulm hungarious L., Adriatic ; 

 Calyptrcea rtigosa Desh. 



Fam. Ampullariadae, (Doppelathmer). With branchial and pulmonary cavity. 

 In rivers of hot countries. Ampullaria celebensis Quoy. ; A. pollta Desh. 



Order 2. HETEROPODA.* 



Pelagic Gastropoda with fin-like foot, large projecting head and 

 highly-developed moveable eyes. Dioecious. 



The body (fig. 521) of the Heteropoda is usually cylindrical and 

 elongated and prolonged into a proboscis-like projecting head, which 

 carries large well-developed eyes and tentacles, and encloses a power- 

 fully-armed protrusible tongue (fig. 514 a). The main peculiarity of 

 the body consists in the formation of the foot, the anterior and 

 middle portion (pro- and mesopodium) of which is modified to the 

 form of a leaf-shaped fin, often provided with a sucker (fig. 521 S) 

 while the hinder section (metapodium) is considerably elongated and 

 extended far backwards, and seems to form the caudal continuation 

 of the body. The visceral sac is either spirally twisted, and en- 

 closed by a mantle and spiral shell (Atlanta), or has the form of a 

 saccular and projecting mass, which is placed at the limit of the 

 hinder region of the foot, and is likewise covered by the mantle and 

 a hat-shaped shell (Carinaria, fig. 521); or finally the visceral sao 

 is reduced to a very small, scarcely-projecting nucleus, which is 

 covered on the front side by a membrane with a metallic lustre and 

 is completely without a shell. 



The nervous system is more highly developed than that of any 

 other Gastropod. The two large eyes are placed near the tentacles 

 in special capsules, in which they are moved by several muscles. The 



* Souleyet. " Heteropodes. Voyage autour du monde execute' pendant les 

 annees 1836 et 1837 sur la corvette la Bonite, etc," Tom II. Paris, 1852. 



K. Leuckart. "Zoologische Untersuchungen,' 1 Heft III. Giessen, 1854. 



C. Gegenbaur. " Untersuchungen iiber Pteropoden und Heteropoden." 

 Leipzig, 1854. 



H. Fol. " Sur le De>eloppement des H6t6ropodes." Arch, de Zool. experim. 

 Tom V., 1876. 



