Fig. 12. Gonioba6is Nebrascensis 565 



TJ, «. Dorsal side of an adult, natural size, of the type-specimen. 



I2,b. An opposite view, showing aperture a little too ranch rounded below. [See wood-cut 



iu text.] 

 12, e. Same view of a smaller specimen. 

 12, d. An opposite view of last. 

 12, e. Dorsal view of a smaller individual. 

 12,/. An opposite view of last. 

 12, g. An aperture view of a still smaller individual. 



12, h. Magnified surface-markings, nearly as seen on some very well preserved specimens, under 



a lens. 

 Fig. 13. Valvata subtjmbilicata 090 



13, a. Under side and umbilicus of the type-specimen, as seen, magnified to about three times 



the natural diameter. 

 13, b. Au upper-side view of same, magnified as above. 



13, c. Au aperture view of same, magnified. 



Fig. 14. Goniobasis tenuicakinata 566 



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



14, b. Au opposite side view of same, showing aperture, etc. 

 I 1. c. Same view as last, magnified. 



Fig. 15. C'ampeloma multistiiiata 588 



15, a. A small specimen. 



15, b. The larger type-specimen of the same, showing aperture, natural size. 

 15, c. A magnified dorsal view. 

 15, d. Au opposite view of same. 



15, e. .Surface-markings, magnified. 



Fig. 16. Bulinus longiusculus 541 



16, «. A dorsal view of type-specimen. 



16, b. A veutral view of same, showing aperture, etc. 



Fig. 17. Bulinus rhomboideus 542 



An aperture view of the type-specimen. 

 Fig. 18. Micropyrgus minutulus 575 



18, a. An aperture view of type-specimen, magnified to nine and a half diameters. 



18, b. Dorsal view of same. 



43-2 



