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. Faminy 5. Gaprytpan, Gray. Visceral 
mass and shell conical; head flattened ; pulmonary cavity aquatic, but 
without a branchia ; genital orifices separated. Genus—Gadinia, Gray. 
Famity 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. Famity 7. Limnartpan, 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- 
Fria. 174. 
Siphonaria algesirae, 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 osphradial 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. Faminy 8. PompHotyaipDaxn, 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, Gerstteldt ; shell 
umbilicated, with convex whorls; tentacles slender; Lake Baikal and 
California. Faminty 9. PLranorpipaE, 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. Famity 10. ANcyLIpAE, Menke. Shell conical, not 
spirally coiled; tentacles short and compressed ; inferior pallial lobe 
