136 THE NAUTILUS. 



somewhat inclined to be gibbous. Aperture small for the genus and 

 nearly round, obtusely angled above. Columella concave with a 

 heavy, flat callus, which extends unbroken between the extremities 

 of the lip leaving the umbilicus scarcely exposed. Lip simple, some- 

 what flattened along the basal portion and obtusely angled at its 

 junction with the columella. Alt. 3, diam. 2^ mm. 



Coosa river, five miles above Wetumpka, Ala. (type locality), also 

 at Wetumpka and near Wilsonville. 



Only a few specimens of this species were found by Mr. Hinkley 

 at any of the above localities, " never more than one in the same 

 place, and always on the under side of rock in swift water." Un- 

 fortunately all the specimens are badly eroded so that it is impossible 

 to give the apical characters. No young specimens that can be re- 

 ferred to the species were found. This species is remarkable for its 

 elevated amnicoloid shape and deeply constricted whorls, but the 

 heavy columellar callus reveals its generic affinities. 



Somatogyrus nanus n. sp. PI. v, fig. 4. 



Shell very small, imperforate, conic-globose, pale greenish-yellow, 

 smooth, shining. Spire very short and rapidly acuminating to the 

 sub-acute apex. Whorls 3, those of the spire but slightly convex, 

 separated by a shallow suture; the body very large, forming most of 

 the shell, convex, somewhat flattened toward the suture. Aperture 

 quite narrowly-angled above, widening and regularly-rounded below. 

 Columella concave, flattened, with a heavy callous, which entirely 

 covers the umbilicus and becomes thin and transparent on the pari- 

 etal wall. Alt. 2|, diam. 2^ mm. 



Coosa river, five miles above Wetumpka, Ala. (type locality), also 

 at Wetumpka, Wilsonville and Fort Williams Shoals above Farmer, 

 Ala. 



This little species is apparently the most abundant form in the 

 Coosa. It was "found in all places on rocks in swift water, scattered 

 or collected in bunches of any number up to 25 or 30." It is well 

 characterized by its small size and the short, acute apex, which with 

 large body whorl and slightly-impressed suture, gives a peculiar 

 mamilliform shape to the shell. The shells are almost invariably 

 covered with a thin, greenish deposit, which under the microscope 

 appears to consist of innumerable, oval granules, closely but irregu- 

 larly agglutinated on the surface. 



