GENERA CUMA, ALAUNA, AND BODOTRIA. 



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The abdomen is short and thick, seven-jointed, the last joint being produced into 

 a long spine which is spiniferous on either edge ; the anal aperture is seen near 

 the base of this segment. The caudal styles arise from the sixth segment, and 

 they are much more complicated that those of the foregoing genera. The first 

 segment is slightly clavate, longer than the seventh abdominal segment, and 

 armed with a single row of spines on its inner edge. The internal scale consists 

 of one joint only ; it is very spiny, and is about half the length of the external. 

 The external scale is composed of three joints, the first two of which are equal 

 in length to one another ; the third is about twice the length of both of these, 

 and is very spiny at its extremity. Long, half-an-inch. Ilab. Frith of 

 Forth. 



Having only obtained one specimen of Alauna rostrata, and 

 one also of Bodotria arenosa, I have not been able to examine the 

 structure of these two genera satisfactorily. 



Genus BODOTRIA, mihi. 



Generic Characters. The first, second, third, fourth, and fifth abdominal segments 

 are each armed with a pair of bifurcated finlets. The two terminal scales of the 

 caudal styles are single-jointed. 



