124 PLECTOGNATHI. 



Yates, of that place, to the Boston Society of 

 Natural History, in whose cabinet it has been de- 

 posited. 



OSTRACION BICAUDALIS. 



The body is marbled, and dotted, as it were, 

 with black. Near the vent, two spines, are sent 

 directly backward, on the plane of the abdomen, 

 whose points approximate a very little ; these 

 are sharp, stiff, and hooked, much like a canine 

 tooth. Writers place the locality of this ge- 

 nus in the Indian seas ; but it is now morally 

 certain that it also exists in this northern latitude, 

 as all the specimens which have been cast on land, 

 could not have been lost by collectors of curiosi- 

 ties, from homeward-bound vessels. Besides, the 

 cutaneo-elastic substance which unites the fins, 

 tail, lips, &z,c.,to parts within the tri-cornered shell, 

 shows most convincingly that it had not been long 

 dead. 



We possess various smaller specimens, from 

 Trinidad, but this, compared with them, is vastly 

 more interesting. It measures not far from four- 



