TABNIOGLOSSA. 



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. Paludinn Lam., river- 

 snail. 



Fam. 16. Valvatidae. A bipectinate ctenidium projecting freely on the left 

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

 Hermaphrodite. Fresh-water. Valvata Midler. 



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. Ceritliium Adanson ; Cerithidea Swainson ; Triforis 

 Deshayes ; Laeococlilis Dunker and Metzger ; Potamidcs Brongniart. 



The Planaxidae (PI an axis Lam.) and the Modulidae (Modulus Gray) are 

 allied here. 



FIG. 314. Cassis sulcosa (after Poli, from Lang), a shell ; 6 anterior canal or spout for the 

 siphon ; c siphon ; d head ; g proboscis ; c 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. Mel i it in 

 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 ; Caecum Fleming. 



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

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

 Brag. 



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; Terebellum Klein; Rostellaria Lam. 



