94 Trans. Acad. Sci. of St. Louis. 



Jefferson Co. (1) ; Fern Glen, St. Lonis Co. (5) ; 

 Morgan Co. (6) ; Jefferson City, Cole Co. (14) ; 

 River bluffs, Moniteau Co. (13); McBaine, 

 Boone Co. (9) ; Providence, Boone Co. (7) ; 

 Boonville, Cooper Co. (28); Bear Creek, Ma- 

 rion Co. (20) ; Pineville, Macdonald Co. (Walker 

 Coll.) ; Pettis Co. (Walker Coll.) ; Arcadia, Iron 

 Co. (Baker); St. Louis ( Smitlisonian Coll.); 

 Callaway Co. (Greger). 



Postpliocene :— Providence, Boone Co. (22), 

 (12) ; Lupus, Moniteau Co. (15). 



Those from the southern counties are of heavier and 

 coarser stria? than the others, but the specimens from 

 the river bottom in Scott county have much less promi- 

 nent striae than those from Benton in the same county. 

 In all of the lots are found specimens with a single lip 

 tooth, and others with two, and sometimes one without 

 either. Pilsbry has defined appressa (Nautilus, Volume 

 VII, p. 140) as having no microscopic spiral lines, but 

 this was criticised by Wetherby. However, in none of 

 the above are found the microscopic lines as given in the 

 type description. 



Those from New Madrid county are the largest, 17 to 

 21 mm. ; from Jefferson City they are 15 to 16 mm., with 

 fine strife. From the river bluffs in Moniteau county one 

 would expect the same size as at Jefferson City, but they 

 are distinctly larger, 16 to 18 mm. At Boonville, also on 

 the Missouri river, they are from 14 mm., and a number 

 of the shells do not have the umbilicus covered. This is 

 markedly so also of a shell from St. Francois county. 

 From Ste. Genevieve the shells are very much like those 

 from central Missouri. The Cape Girardeau shells vary 

 from the small, light colored, very finely striated, to the 

 larger dark colored coarsely striated form. One shell 

 shows that by some injury a part of the shell was broken 

 away, and a new lip more than a half whorl short of the 

 original one formed. Both teeth remain, the old one 



