52 THE NAUTILUS. 



wall, the entire aperture is quite heavily calloused within 

 Umbilicus quite large, 



Alt. (apex eroded) 4, diam. 4 mm. 



Types (33900 Coll. Walker), from the Ouachita River, 

 Arkadelphia, Ark. Cotypes in the collection of Rev. H. E. 

 Wheeler. 



This species, named after its discoverer, while related to the 

 shouldered species of Somatogyrus from Alabama, is quite dis- 

 tinct by reason of its larger umbilicus, flatly shouldered body 

 whorl and elevated apical whorls. 



Somatogyrus amnicoloides n. sp. Fig. 3. 



Shell small, subglobose, narrowly umbilicate, rather thin, 

 pale horn-color, smooth, with very fine, regular lines of growth. 

 Spire obtusely elevated, flatly rounded. Apical whorl scarcely 

 at all everted, only slightly elevated above the second whorl, 

 not constricted by the suture, which is well impressed, but 

 vertical, sculpture practically obsolete. The second whorl is 

 convexly rounded, but not high. The third whorl is propor- 

 tionately higher, rounded above and less so below. Body- 

 whorl globosely rounded. Aperture angled above, wider and 



Fig. 3. Somatogyrus amnicoloides. Fig. 4. Somatogyrus cRAssiiiABRis. 



obliquely rounded below. Lip sharp, but callously thickened 

 within, meeting the columella in a projecting, broadly rounded 

 angle. Columella nearly straight, scarcely at all thickened, 

 inner lip adnate to the body-whorl on the parietal wall. Um- 

 bilicus rather narrow, but conspicuous. 



Alt. 3.5, diam. 2.75 mm. 



Types (No. 40012 Coll. Walker), from the Ouachita River, 

 Arkadelphia, Ark., collected by the Rev. H. E. Wheeler. Co- 

 types in his collection. 



