THE NATURAL HISTORY SURVEY. 327 



While moving about, the rostrum is kept constantly in motion, 

 as well as the long, filiform tentacles, and the lingual apparatus 

 may be distinctly seen, as in Limncea, the mouth being a long, 

 vertical slit in the end of the rostrum. The animal frequently 

 comes to the top of the water and, pushing its rostrum above 

 the surface, will remain in this way for hours. 



Livescens has been found in a fossil state on Balmoral 

 avenue, north of Bowmanville, on the corner of Sheffield and 

 Lincoln avenues, and in sand banks on the lake shore, north 

 of Graceland avenue. 



1323. Goniobasis livescens depygis Say, pi. xxxv, fig. 8. 

 Melania depygis SAY, New Harm. Dissem., p. 291. 

 Melania occulta ANTHONY, Proc. Phil. Acad., p. 5, 1860. 



Shell: Differing from typical livescens in being narrower, 

 the two color bands brighter and more conspicuous and the 

 columella not tinged with purple. 



Length. Width. Aperture Length. Width. 



23.00 8.50 9.00 4.50 mill. (coll. Ferriss.) 



17.25 7.75 8.00 4.50 " (coll. Ferriss.) 



Animal, Jaw and Dentition: As in livescens. 



Genitalia: Not observed. 



Distribution: Same as livescens. 



Geological distribution : Pleistocene; Loess. 



Habitat: Same as livescens. 



Remarks: After the examination of several thousand 

 specimens from Northern Illinois, and after consulting with 

 several conchologists, it seems imperative that depygis must 

 become a variety of livescens, and it is an open question if it 

 is entitled to even varietal rank. The writer has before him a 

 set of Goniobasis in which there is a perfect gradation from the 

 heavy, swollen livescens, with dark shell and purple tinged col- 

 umella, to the most graceful depygis, with light shell and dark 

 spiral bands, and white columella. The variety has been found 

 only at Hickory Creek. 



FAMILY AMNICOLID^:. 



"Tentacles elongated, with eyes at their outer bases. Oper- 

 culum subspiral or concentric. Shell small, globular or elon- 

 gated, spiral. Aperture broadly oval, lip continuous. Gener- 

 ally umbilicated."* 



*Tryon, continuation of Haldeman's monograph, No. I, p. 8. 



