LARVAE OF DECAPOD CRUSTACEA 317 



In Stage III the telson widens towards the end and spines 1-4 are close together near 

 the posterior angle. 



a. Rostrum. 



Fig. 17. Thalassinid B.R. III. 



b. Telson. c. Telson, stage III. 



GROUP II 

 Without epipods 



Group II includes species of which the only common character is the absence of 

 epipods, and it is doubtful whether too much importance has not been attached to this 

 fact. Group II A seems to be really closely allied to Group I A, and to belong to the 

 Axiidae, though species B.R. V is difficult to place. The telson is of an intermediate 

 type, and the arrangement of the posterior spines is unlike that of any other form. 



Group II B is purely artificial, since species D. XIII is probably a young form of 

 D. X, and B.R. VI appears to be a Callianassid, though with a telson of quite typical 

 "A" type. 



Group II C consists of species which are almost certainly Callianassa of type I ; in 

 fact D. XIV has most of the characters of C. subterranea. 



Group II D is again doubtful, but the assumption is made that the absence of 

 epipods is sufficient to determine them as Callianassidae. At the same time such an 

 assumption presents great difficulties. In the first place no Callianassa of this type is 

 known with an exopod on leg 5, and in C. laticauda exopods are present only on legs i 

 and 2. The fact that the mouth parts are rudimentary, whereas they are fully developed 

 in European species, is not a serious difficulty, since they are rudimentary also in some 

 Callianassa described from the Red Sea (Gurney, 19376). 



While it may probably be accepted that species D. XVII and B.R. X, which have 

 no exopod on leg 5 and three pairs of pleopods, are actually species of Callianassa the 

 other two are uncertain. Species B.R. IX has an exopod on leg 5 and four pairs of 



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