1817.] GENUS MONOLEPIS. 159 



years ago, on the coast of South Carolina; they had been 

 preserved in spirits, bat were lately : iken out, to be more 

 conveniently arranged in the cabinet, by exposure to the 

 air and the evaporation of the liquid, they had become 

 considerably contracted, but the striking character of the 

 spinous tarsi, even if the other traits were deceptive, from 

 desiccation, is very sufficient to distinguish it from the 

 preceding species. 



'j'he characters of the remarkable animals of which I 

 have here thought proper to construct a new genus, widely 

 differ in essential particulars, from those of all other gene- 

 ra, as defined by naturalists. From a transient view, or 

 slight examination, we would be disposed to refer this 

 genus to the first order of Brachyura, in consequence of 

 the great similarity of habit, which its species bear to that 

 of the individuals of that order. But however closely it 

 may be allied to the Brachyu rae in point of external figure^ 

 it is very certain that the character, drawn from the con- 

 formation of the caudal lamellae, is of itself sufficient to 

 exclude it absolutely from that natural group of the Crus- 

 tacea, in which the tail is invariably simple, or destitute 

 of lateral appendices of any kind. 



The precise situation it ought to occupy in the order 

 to wliich I have assigned it, may perhaps be, with more 

 difficulty, determined,* This difficulty does not arise from 

 any proximity, which Monolepis can claim, with any of 

 the existing genera, but, in consequence of its remoteness 

 from either of them. There is no genus of the genuine 

 Macroura which is furnished with a less number than two 

 foliaceous appendices on each side of the tail, and but one 

 (Porcellana) that has the abdomen inflected into a groove 

 beneath the body. The resemblance of this last genus 



