16 University of Michigan 
23). It is a considerably more elongated and compressed form 
than are the others, and the epidermis is golden-brown with 
indistinct, brownish rays. The growth-lines are well marked 
and give this shell a somewhat concentricly wrinkled appear- 
ance; otherwise it appears quite without ornamentation. 
Anodonta globosa Lea, subsp. nopalatensis (Sowerby) 
(1867).—Plate V, fig. 26. One left valve, in good condition, 
from the Rio San Juan (H, vu, c) ; picked up on the bank by 
' Dr. Ruthven. 
The epidermis is radially striate, % mm. apart, while ante- 
rior to the umbones are etched very distinct, fine furrows, 4 
to 6 mm. apart. The ventral margin is distinctly sinuate, but 
this may in part be caused by an injury about 3 cm. dorsad; 
but the shell is flattened to slightly concave centrally, even 
above this. The color of the epidermis is dark brownish-olive, 
to rust-colored towards the beaks. 
This specimen is from within a few miles of the type locality 
of nopalatensis, as worked out by von Martens (1900); A. 
globosa globosa is froma lake near the mouth of the same river 
system. With its extremely high and full beaks, great infla- 
tion and sloping dorsal margins, this form appears to be more 
distinct from globosa (adult specimens in the A. N. S. P.) 
than is A. tabascensis Mo. as figured by Fischer and Crosse 
(1894). 
MEASUREMENTS 
A 
oR Bl. ele 
Se ae 
Snes o =I 
= » oO ~~ oO 
~ SG vo a, 
o 0 4 e o 
cco) (by SG =} mas) oS 
a la 
A. globosa Wea. 100 72 52 (type, Simpson, 1914) 
A. tabascensis Mo. 178 69 50 (F. and C., 1894) 
A. nopalatensis 
Swby. 150: (73 (F. and C., 1894) 
Plate V, fig. 26 150 75(112.5) 68(102) 
