THE GASTROPODA 



185 



conical ; tentacles atrophied ; head expanded ; genital orifices contiguous ; 

 marine animals, with an aquatic pallial cavity containing secondary 

 branchial laminae. Genera Siphonaria, Sowerby (Fig. 174). Hercynella, 

 Kayser ; from the Devonian. FAMILY 5. GADINIIDAE, Gray. Visceral 

 mass and shell conical ; head flattened ; pulmonary cavity aquatic, but 

 without a branchia ; genital orifices separated. Genus Gadinia, Gray. 

 FAMILY 6. CHILINIDAE, Dall. Shell ovoid with a short spire, wide 

 aperture, and folded columella ; tentacles broad and flattened ; inferior 

 pallial lobe thick ; visceral commissure still twisted. Genus Chilina, 

 Gray ; rivers of Patagonia. FAMILY 7. LIMNAEIDAE, Broderip. Shell 

 thin, dextral, with prominent spire and oval aperture ; tentacles angular 

 and flat ; no inferior pallial lobe. Genera Limnaea, Linnaeus (Fig. 

 107); shell wholly external, with a pointed spire; British. Amphi- 



Fio. 174. 



Siphonaria algefirac, removed from its shell. I, heart in the pericardium ; II, kidney ; III, 

 pallial intrapulmonary gill ; IV, mantle ; V, columellar muscle ; VI, anus ; VII, pneumostome, 

 to the left of which (in the pulmonary cavity) is the osphradinl papilla ; VIII, inferior pallial 

 lobe; IX, renal pore. 



peplea, Nillson ; shell in great measure covered by the mantle, globular, 

 with a very short spire ; British. FAMILY 8. POMPHOLYGIDAE, Dall. 

 Shell hyperstrophic (ultra-sinistral, that is to say, with an apparently 

 dextral coil) with an obtuse spire ; the animal sinistral. Genera Pom- 

 pholyx, Lea ; tentacles dilated at their extremities ; shell depressed, the 

 last whorl ventricose ; from California. Choanomphalus, Gerstfeldt ; shell 

 umbilicated, with convex whorls ; tentacles slender ; Lake Baikal and 

 California. FAMILY 9. PLANORBIDAE, Adams. Visceral mass and shell 

 sinistrally coiled ; inferior pallial lobe very prominent and transformed 

 into a branchia; tentacles tapering. Genera Planorbis, Guettard ; 

 shell discoid ; branchia not folded (Fig. 89) ; British. Bulinus, 

 Adanson ; shell ovoid with prominent spire ; branchia folded (Fig. 175). 

 Miratesta, Sarasin. FAMILY 10. ANCYLIDAE, Menke. Shell conical, not 

 spirally coiled ; tentacles short and compressed ; inferior pallial lobe 



