120 jMr II. Goodair on (he Genus Cuma. 



to publish tlicm at th.it time under this arrangement. I 

 waited, however, until it could be satisfactorily proved whether 

 they were perfect animals, or, according to the suspicions of 

 M. Edwards, merely the larvae of some Decapodous Crustacea. 

 I have now satisfied myself that they are perfect animals, and 

 at the same time have discovered the types of two new genera, 

 which places the group in a still more interesting point of 

 view. 



I have applied the name Bodotria to one of these genera, 

 and Alauna to the other ;the former being the ancient name 

 of the Firth of Forth, at the mouth of which all these animals 

 were got ; and the latter, the ancient name of the river Forth. 

 The latter of these genera {Alauna) may be the genus Coti- 

 dylurus of Latrcille, as I have never seen that author's de- 

 scription ; but whether it bo so or not there cannot bo any 

 danger in applying the name Alauna. as Condi/hirus had been 

 previously used amongst the Mammalia. 



As I had a greater number of specimens of the Cmna Ed- 

 fvardsli than of any of the others, I have been enabled to make 

 out the structure of that species with greater minuteness. 



These animals are very like small prawns in their general 

 appearance ; but they bear perhaps in this respect a greater 

 likeness to the species of the genus Nebalia than to any other 

 known Crustaceans. 



The shell is hard and brittle, cracking under pressure. All 

 the species are of a pale straw colour. The thoracic portion 

 of the body is large and swollen ; it is composed of six seg- 

 ments ; the abdomen is longer, and is composed of seven seg- 

 ments. 



M. Edwards, in his Memoir on the genus Cuma, published 

 in the 13th vol. of the Ann. des Sc. Nat., considers that the 

 whole of the first and largest segment of the body constitutes 

 the head. In all the specimens which I have dissected, I have 

 found a suture running across this segment, immediately be- 

 fore the middle part of it ; this is observed very distinctly in 

 the Cuma trispinosa, in the Bodotria arenosa, and also in the 

 genus Alauna. The first of these parts I consider to be the 

 head ; the second part as the first thoracic segment. To the 

 first we find attached the rostrum, eyes, antenna-, oi'gans of 



