202 THE CHICAGO ACADEMY OF SCIENCES. 



strongly impressed; aperture ovate or roundly-ovate, generally evenly 

 rounded at the lower extremity and somewhat angled above ; outer lip 

 thin, sharp; inner lip reflected to form a rather broad, flat, excavated 

 projection over the umbilicus, there being a moderately open chink; 

 parietal callus very thin; the inner lip is rolled over and appressed 

 rather closely to the columellar region ; axis forming a series of smooth, 

 hour-glass-shaped pillars. 



Length. Breadth. Aperture length. Breadth. 

 10.50 5.00 5.00 2.50 mill. European spec. 



11.50 6.00 5.75 3.00 " 



7.50 4.25 3.50 2.00 " 



7.50 4.00 3.50 1.75 " " 



6.00 3.50 3.00 1.50 " " 



7.00 4.50 3.50 2.00 " " " 



TYPES: Location not ascertained. 



TYPE LOCALITY: Not known. 



ANIMAL: Not examined. 



JAW, RADULA and GENITALIA: Not examined. 



RANGE: (Figure 15) Europe, northern Asia and portions of 

 Alaska and Yukon Territory. 



The presence of true truncatula in America, except in portions of 

 Alaska, Yukon and the Aleutian Islands, is seriously to be questioned. 

 The majority of the specimens examined have been referable to Galba 

 parva Lea. Further investigation, however, may discover it in other 

 portions of northwestern North America. 



RECORDS. 



ALASKA: Ponds near Yukutat Bay (Kincaid) ; Ladyginsk, Behring Island 

 (Stejneger) ; Kadiak (Jeffreys). 



YUKON, BRITISH AMERICA: Lake Marsh (Randolph). 



GEOLOGICAL RANGE: Pleistocene. There are no American rec- 

 ords. 



ECOLOGY: Inhabits marshes, ditches, muddy streams, etc. 



REMARKS: Truncatula may be distinguished by its turreted 

 whorls rather narrow shell and ovate aperture. It resembles humilis 

 and parva, but these species are quite distinct, having a differently 

 shaped spire and inner lip. 



It is closely allied to cubensis, having somewhat the same form 

 of inner lip, but may be distinguished by its narrower shell, more at- 

 tenuate spire and less rotund body whorl. The inner lip is not as 

 roundly folded in truncatula as in cubensis, being rather a little exca- 

 vated in the middle ; the umbilical chink is also smaller in truncatula. 



