Page. 

 Fig. 11. Planorbis convolutus (varieties) 538 



11, a. A small internal cast, left side (broken at the aperture). 



11,6. A right-side view of same. 

 11, c. An aperture view of same. 



11, d. A right-side view of a more ventricose internal east, broken at the aperture. 



11, e. An aperture view of the same. 

 Fig. 12. Planorbis convolutus (type) 53t> 



12,0. A right-side view of an internal east, with the outer volution broken across near the 

 aperture. 



12,6. An aperture view of same. 

 Fig. 13. Bulinus subelongatus MO 



13,(1. An aperture view of the type-speciineu, which has its lipjiroken. 



13, 6. An opposite view of the same. 



Fig. 14. Campeloma vetula 587 



14, ((. A dorsal view of the type-specimen. [Lip too narrowly produced below.] 



14, b. An aperture view of same. 



Fig. 15. Viviparus Conradi 579 



15, a. An aperture view of the type-specimen, which is of medium size, and has its outer lip 



somewhat broken and apex wanting. 

 15, 6. Same view of a smaller specimen in same condition. 

 15, c. An aperture view of a large specimen, with its outer lip broken, and the angle of the 



body-volution nearly obsolete. 

 15,(7. An opposite view of same. 



Fig. 16. Planorbis (Bathyomphalus) amplexus 539 



lfi, o. Upper or right side of the type-specimen, natural size. 



in, 6. The same, magnified. 



10, 6 (6is). (A little to the right of the middle of the plate.) Form of aperture, as deter- 

 mined from a break across the outer volution. 



16,(i. An under side or umbilical view, magnified. 



Hi, e. Surface-markings of upper side, magnified. 

 Fig. 17. GoNiOBASrs .' mtitortuosa 569 



17, a. A dorsal view of the type-specimen, natural .size. 



17,6. The same, magnified, but showing the body- volution proportionally too broad. [For 

 an aperture view, see wood-cut in text.] 



42-2 



