128 Mr H. Goodsir on the Genus Cuma. 



row of spines on its inner edge. The internal seale 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 two first of ■which 

 are equal in length to one another; the third is about twice the length 

 of both of these, and is verj' spiny at its extremity. 

 Long, half-an-inch. Hab., Frith of Forth. 



Having only obtained one specimen oi Alauna rostrata, and 

 one also of Bodotria avcnosa, 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 arc each armed with a pair of bifurcated finlets. The two 

 terminal scales of the caudal styles arc single-jointed. 



Bodotria arcnosa, mihi. 



Description. — The carapace is almost oval, rostrum awanting, tliat part 

 of the carapace being mcrcl}' rounded off. The superior antenna3 are 

 quite obsolete. The inferior pair are of considerable length, and are 

 terminated by means of two long spines. 

 The ambulatory division of the first pair of legs has the first joint of a 

 very great size, being very much flattened and slightly curved. The 

 four remaining joints, together with the internal thumb, arc very spin}'. 

 The natatory division of the leg is six-jointed, the four last joints giving 

 rise to as many long spiniferous spines, which are articulated at their 

 distal halves. The external edge of these spines arc spiniferous at the 

 articulated half only. The ambulatory division of the second pair of 

 legs has the first segment very broad, and tapering gradually towards 

 its distal extremity, from which arises a very long, articulated, and 

 spiniferous spine. 

 The abdominal finlets arc five in number. They are composed of two 

 parts, viz., the first or pedicle, and the second or bifurcation ; the pe- 

 dicle is of considerable length, from the extremity of which there arises 

 two scales, which are armed on their margins with long spiniferous 

 spines, which are much longer than the finlet itself. 

 The first segment of the caudal styles tapers very slightly, and the two 

 terminal scales are each of them single-jointed, and end by means of 

 very fine points. The external is armed at its extremity with two 

 spines. Long, 5 lines. 

 This genus forms doubtless a link between the Stomopoda of M. Edwards 

 and the higher Crustacea. 



In their habits all these animals seem to agree. I have not 

 been able to observe any thing peculiar in them. They swim 

 with very great rapidity, and on stopping they fall to the bot- 

 tom on the sand or gravel, without attempting to lay hold of 

 anything, as I have already remarhed, seldom using their feet 



