THE NAUTILUS. 135 
Remarks.—This species belongs to the group of which U. trigonus 
Lea, may be considered the type, although differing much from that 
species in outline, beaks and in the uniform roundness of the sides. 
It also has certain characters indicating a relationship with U. 
Ridellii Lea, U. Chunii Lea and U. cuneus Con. It differs from the 
first in having the posterior apex lower and more or less biangul- 
ated; the posterior margin rounded, instead of straight; posterior 
margin without the hip peculiar to U. Ridellii; the cardinal teeth 
are heavier and not pyramidal; and differs most remarkably in the 
character of the beak undulations. From U. Chunii Lea, it differs 
in having a greater depth of cavity ; more massive and higher um- 
bones and swollen sides without depressions ; much shorter poste- - 
rior extension; base not emarginate; entire absence of rays and 
the same difference in beak undulations that distinguishes it from 
U. Ridellii Lea. It differs from U. cuneus Con. in being smoother ; 
lighter colored epidermis; much larger opening to the umbonial 
cavity ; cavity of the shell much deeper and more uniformly rounded ; 
lateral teeth more slender and the species never attains the extreme 
size of U. cuneus, the declivity of the posterior slope is much steeper ; 
the ligament shorter; without the anterior subtruncation, and it is 
never cuneiform. 
The peculiar undulations of the beaks amply distinguish it from 
any other known species. 
Some twenty-five specimens have been critically examined which 
maintain a remarkable constancy in all the characters. 
It is named in honor of Mr. Lorraine S. Frierson of Frierson 
Mill, La. who is a zealous student and collector of Unionide. 
ON CERTAIN ABNORMAL SPHAERIA. 
BY BRYANT WALKER, DETROIT, MICH. 
The peculiar characteristics of the hinge-teeth of the American 
species of Spherium and Pisidium have been almost totally ignored 
by Prime and the earlier writers in their descriptions of the various 
species which they established. With the exception of some of the 
descriptions of the more recently described species, nothing but the 
most general remarks upon the subject are to be found in the Amer- 
ican literature upon these genera. Among the European concholog- 
