292 



THE CHICAGO ACADEMY OF SCIENCES. 



Acella galbana LEWIS, Bull. Buff. Soc. N. H., 1874, p. 135. 

 Limncea traskii MARTENS, Mai. Blatt., XIX, p. 78, 1872. (?) 

 SHELL: Small, subovate, rather inflated, thick; periostracum 

 whitish or yellowish ; surface shining, growth lines coarse, prominent, 

 without spiral lines ; whorls 5, convex, roundly shouldered, rapidly 

 increasing in diameter , the body whorl very large and somewhat flat- 

 tened on the periphery; nucleus small, flatly rounded, dark colored, 

 similar in form to that of obrussa; spire usually short, broadly acutely 

 conical, generally occupying about half the length of the shell ; sutures 

 rather deeply impressed ; aperture ovate, generally rounded above and 

 below ; outer lip simple, acute ; inner lip erect, forming a rather broad, 

 fiat reflection over the umbilical region which emargins the umbilical 

 chink and which is without plait-like thickening; there is a thin wash 

 of callus on the parietal wall ; umbilical chink narrowly open ; speci- 

 mens are frequently imperforate. 



4.25 ' 



4.75 



5.00 



4.00 



3.00 



3.75 



5.50 



6.00 



5.00 



5.50 



4.75 



TYPE : Academy of Natural Sciences, Philadelphia, one specimen, 

 No. 58821. 



TYPE LOCALITY: Marl pit near Franklin, New Jersey. 



ANIMAL, JAW, RADULA and GENITALIA : Unknown. 



RANGE (Figure 32) : From New Brunswick and Anticosti Island 

 west to Washington, Alaska south to southern Indiana and southern 

 California. 



Galbana is not found at present farther south than the Transition 

 life zone, though it ranges north well into the Boreal life zone. The 

 marl deposits, however, show that in Post-Glacial Times it ranged 

 south in Indiana (Upper Austral) and extended as far north as the 

 Arctic circle. It is exceedingly abundant in the marl deposits of New 

 lersey, New York, Michigan and Indiana, and must have been at one 

 time one of the commonest of the smaller Lymnaeas. The wide gaps 

 in its distribution show that much work is yet to be done before its 



