DIPLODON 1265 



each ; nacre dirty white, lurid in the cavities, thickened and 

 soUd in front. 



Length 71, height 35, diam. 20 mm. 



Length of a younger shell 50, height 26, diam. 12 mm. 



Patagonia ; Chile ; Us Perus, San Paulo, Brazil. 

 Unto frensellii von Ihiiiring, Arch, fiir Nat., 1893, p. 3, pi. 



iv_, fig. 12. 

 Diplodon frensellii Simpson, Syn., 1900, p. 882. 



Dr. von Ihering sent two shells to the National Museum 

 which are probably this species. The form is oblong and al- 

 most evenly rounded at the ends, there is no posterior ridge, 

 but one or two feeble raised lines on the posterior slope. The 

 shell is quite solid and strongly sulcate, of a peculiar yellow- 

 ish-green with a bronzy or metallic tint. Von Ihering states 

 that it is sometimes brown. 



Diplodon huapensis Bartsch. 



"Shell thin, elongate, elliptical, drawn out posterio-ventrally 

 into a blunt beak, compressed dorsally, from a line extending 

 from the umbones to the posterior-dorsal margin of the beak 

 and somewhat pinched in its subcentral ventral half. Dorsal 

 margin slightly curved, its posterior third sloping regularly 

 obliquely downward. Anterior margin abruptly curved, fall- 

 ing ofif a little more gradually toward the ventral than the 

 dorsal edge. Posterior extremity evenly rounded. Ventral 

 margin somewhat concave in the middle. Periostracum brown 

 on the posterior dorsal portion of the shell, grading to wax- 

 yellow streaked with brow'n on the anterior ventral parts. Sur- 

 face marked with numerous lines of growth, the stronger ones 

 of which are usually darker colored than the general surface, 

 and numerous fine, crinkly, radiating lines, which are best de- 

 veloped on the anterior half, and gradually diminished in 

 prominence posteriorly. Beak cavities shallow\ Pseudocardi- 

 nals in the right valve two. narrow, weak, sublamellar, and 

 very oblique, the dorsal one decidedly notched and stronger 

 than the ventral, v^^hich is rugose. Left pseudocardinal nar- 

 row, slender, slight, notched, and cut into manv fine tubercles. 



