52 ON A GENUS AND SPECIES OF THE CHAKACINES. 



air bladder is about five inches long by seven-eighths of an 

 inch in greatest diameter, gradually tapering behind the 

 middle ; its walls are much thinner and not at all rigid. 



The stomach is filled with parts of various plants, for 

 the most part of some broad-leaved succulent cabbage-like 

 aquatic plant. In cropping such thick leaves an upper lip 

 would only be an obstacle. As the upper teeth are flush 

 with the outline of the face and include both lower teeth 

 and lip when the mouth is closed, the arrangement is ad- 

 mirably suited to the habits of the fish. 



Total length sixteen and one-fourth, head two and three 

 fourths, and depth four and seven-eighths inches. 



Color nearly uniform, slightly brownish on the back, 

 lighter beneath, silvery. 



Hob. Santa Clara, on the Rio Mucury, Brazil, where 

 it was secured for the Museum of Comparative Zoology by 

 Messrs. Hartt and Copeland of the Thayer Expedition. 



The position of this genus in the system is close to the 

 genera Tetragonopterus and /Scissor. The species is named 

 in honor of Dr. Henry Wheatland, President of the In- 

 stitute, in token of appreciation of his friendly interest 

 and sympathy in favor of ichthyology and ichthyologists. 



