i6 



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, vii, 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 from a 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 



