FRESHWATER AND LAND SHELLS. 61 



a little out of our way, in pursuit of a bear crossing from the main. 

 After resting a while, we re-embarked, and continued on our voyage, 

 coasting the east shore of the island to the upper end; here we 

 landed again, on an extended projecting point of clean sand and peb- 

 bles, where were to be seen pieces of coal sticking in the gravel and 

 sand, together with other fragments of the fossil kingdom, brought 

 down by inundations and lodged there. We observed a large kind of 

 muscle in the sand ; the shell of an oval form, having horns or protube- 

 rances near half an inch in length, and as thick as a crow-quill, which 

 I suppose serve the purpose of grapnels to hold their ground against 

 the current. Embarked again, doubled the point of the island, and 

 arrived at Point Coupe in the evening." — Travels^ p. 431. 



I have several times endeavoured to procure the shell mentioned by 

 Bartram, but have not been fortunate enough to succeed. The speci- 

 men figured here belongs to Professor Shepard, to whom I am indebt- 

 ed for several other fine species from the same locality. Professor 

 Shepard informs me that he received three individuals from his friend 

 Mr Cowper, with the remark that they were obtained with difficulty 

 during the last summer from a bar in the Altamaha. Two of these 

 specimens were given to Professor Ravenel, to whose kindness I am 

 indebted for the promise of one of them. 



Unio pliciferus. Plate XVII. fia:. 53. 



&• 



Testa ellipticd, incequilaterali, subinflata, posiich undulata ; valvulis antic^ crassioribus ; 

 natibus prominulis ; epidermide atro-viridi; dentibus cardinalibus submagnis ; lateralibus 

 rectis ; margarita purpurea. 



Shell elliptical, inequilateral, somewhat inflated, undulated behind ; valves thicker 

 before ; beaks rather prominent; epidermis blackish green ; cardinal teeth rather large ; 

 lateral teeth straight ; nacre purple. 



Hab. Mexico. Dr Burrough. 



My Cabinet. 



Cabinet of Dr Burrough. 



Cabinet of Academy of Natural Sciences. 



VI. Q 



