QUADRULA 895 
QUADRULA ANDREWSI! Marsh. 
“Shell smooth, triangular, solid, beaks swollen, incurved, 
shell very inequilateral, compressed and striate at the base; 
obliquely rounded before, obtusely biangulate behind; liga- 
ment rather short, light brown; epidermis reddish-brown, 
maculate; growth lines numerous; rather rough; umbonal 
slope slightly rounded; posterior slope flat, cordate, with very 
indistinct lines from beaks to basal margin; beak sculpture un- 
known; cardinal teeth thick, very much sulcate, single in 
right, double in left valve; lateral teeth thick, short and slight- 
ly curved; anterior cicatrices small and deep; posterior cica- 
trices distinct. small and deep; shell cavity rather deep; cavity 
of the beaks deep and angular; nacre silver white and irides- 
cent. 
Diameter 1.1, length 1.6, breadth 2 (inches). (Marsh). 
Type locality, Holston River, Tenn. 
Quadrula andrewsu Marsu, Naut., XV, 1902, p. T15. 
Quardula andrewse Marsu, Naut., XVI, 1902, p. 8, pl. 1, upper 
two figures. 
“Several years ago Mrs. Geo. Andrews of Knoxville, Ten- 
nessee, sent me a number of these shells. They belong to the 
group of which trigonus Lea is the type, but in no way do 
they resemble that species. There is no species, which they 
closely resemble, except globatus Lea, but it is a very much 
less inflated shell than that species, having a differently colored 
epidermis, rougher and coarser growth lines; at least one-half 
of the disk is covered with wide, dark green spots, and between 
these rows of maculations are very narrow, dark green inter- 
rupted.rays. The outline of globatus is rounded, while my 
shell is triangular.” 
QUADRULA BEAUCHAMPI! Marsh. 
“Shell subtriangular, inflated over the umbones and beaks; 
shell very thick and solid, thicker before; beaks solid, raised 
and incurved; inequilateral, rounded before, obtusely angular 
behind; ligament short, thick, light brown; epidermis yellow- 
ish-brown; growth lines close, and very prominent, almost 
