224 APPENDIX F. SHELLS. 



SHELLS. 



BY PROFESSOR C. B. ADAMS. 



Amherst, Massachusetts, 



December 1, 1852. 

 Dear Sir : I transmit herewith a list of the shells which were col ■ 

 lected in Texas and npon Red river, by Captain Marcy ; 

 And have the honor to remain, your obedient servant, 



C. B. ADAMS. 

 President Hitchcock. 



ACEPHALA. 



1. Unio asperrimus, Lea. 



The specimens have a great profusion of small tubercles on the 

 umbones. One large specimen was taken May 2 2d, at the foot of the 

 Witchita mountains ; 3 mature and 5 young shells were taken in Otter 

 creek, July 13th, near the same place; long, about 100° W. ; lat. about 

 34° 35' N. 



2. Unio, Sp. indet. 



This may be a variety of the preceding ; but with only one decayed 

 specimen, we do not venture to describe it as a new species. It differs 

 in having only a few large tubercles in two radiant series, of which one 

 passes down the middle of the disc, and the other is on the posterior 

 angle. A few small curved ridges proceed from this angle to the liga- 

 mentary margin. No label. 



3. Unio tuberculatus, Barnes. 

 A single valve of a young specimen; no label. 



