TAENIOGLOSSA. 



399 



Fam. 15. Paludinidae. Shell conical or globular, with thick olive-green 

 periostracum ; operculum horny, normally concentric. Snout blunt, tentacles 

 long, eyes on short pedicels outside tentacles. Pedal ganglia elongated into 

 cords ; kidney with ureter. Viviparous. Fresh-water. Paludina Lam. , river- 

 snail. 



Fam. 16. Valvatidae. A bipectinate ctenidium projecting freer^on the left 

 side ; a filiform appendage on the right side ; eyes sessile behind the tentacles. 

 Hermaphrodite. Fresh-water. Valvata Mliller. 



Fam. 17. Ampullariidae. Mantle-cavity divided into a right branchial 

 division containing a monopectinate ctenidium, and into a left half functioning 

 as a pulmonary chamber. Oesophageal nerve-collar in front of buccal mass. 

 Fresh water. Ampullaria Lam. (Fig. 303). Apple-snail or idol-shell. Inhabit 

 lakes and rivers in warmer parts of world, retiring into the mud in the dry 

 season. 



Fam. 18. Cerithiidae. Spire elongated; siphon short; operculum horny. 

 Marine or brackish water. Cerithium Adanson ; Cerithidea Swainson ; Triforis 

 Deshayes ; Laeocochlis Dunker and Metzger ; Potamides Brongniart. 



The Planaxidae (Planaxis Lam.) and the Modulidae (Modulus Gray) are 

 allied here. 



FIG. 314. Cassis sukosa (after Poli, from Lang), a shell ; b anterior canal or spout for the 

 siphon ; c siphon ; d head ; g proboscis ; e eye ; / tentacle ; h foot ; i operculum. 



Fam. 19. Nerinaeidae. Nerinaea Defrance. 



Fam. 20. Melaniidae. Spire elongated; thick, dark periostracum; edge of 

 mantle fringed. Viviparous. Fresh-water in warmer parts of world. Melania 

 Lam. ; Melanopsis Lam. ; Paludomus Swainson. 



Pleuroceridae (fresh- water), Pseudomelaniidae (marine) are allied here. 



Fam. 21. Turritelidae. Shell multispiral or tubular; operculum horny-; 

 head large and projecting; edge of mantle fringed; foot broad. Turritella 

 Lam.; Mathilda Semper; Coecum Fleming. 



Fam. 22. Vermetidae. Shell tubular, attached, irregularly coiled, last coils 

 not in contact; operculum circular. Vermetus Adans., worm-shell; Siliquaria 

 Brug. 



Fam. 23. Strombidae. Wing -shells. Foot narrow, arched, compressed 

 laterally, without ventral sole; snout long; large and elaborate eyes placed on 

 thick pedicels with slender tentacles arising from the middle of the pedicels. 

 Very active, progressing by a sort of leaping movement. Strombus L. ; 

 Ptcroceras Lam., scorpion-shell; Terebcllum Klein ; Rostellaria Lam. 



