358 



Transactions. 



The ovigerous female* differs from the male in having the second antenna 

 more slender, in the absence of dilatation of the joints of the peraeopoda, 

 and in the gnathopoda. In the first gnathopod (fig. 6, gn'^) the basal joint 

 is longer than any of the others, and is of equal width throughout, being 

 about three times as long as broad, the carpus is considerably longer than 

 the propod and widens slightly towards the distal end, the propod is 

 oblong, Tather narrower than the carpus, the palm is transverse, finger 

 slender, not reaching beyond the palm ; all the joints provided with a 

 few stout spiuules arranged in the usual manner. In the second gnathopod 

 (fig. 6, gn^) the basis is much widened, its hind margin straight, anterior 

 sinuous and fringed with fine spinules, the greatest width at the proximal 

 third being about one-half the length ; in the remaining joints, in the 

 branchia, and in the large incubatory plate the appendage presents the 

 characters common to the genus. None of the peraeopoda have any joints 



Fig. 6. — Orchestia miranda., female, gii^, first gnathopod ; 

 ga"^, second gnathopod. 



expanded ; in the fifth the basis has the posterior margiii convex and 

 serrate and not produced downwards beyond the extremity of the joint ; 

 the following joints are slender and of the usual form. 



The immature males resemble the females except in the gnathopoda, 

 which appear to acquire the special character of the male early, though 

 they are for a time much smaller than in older individuals . In quite young 

 males, though the gnathopoda have already acquired the characteristic 

 form, the antenna and the peraeopoda show no sign of dilatation, but are 

 quite like those of the females. Among my specimens are numerous transi- 

 tional stages from this up to the widely dilated peraeopoda of the adrdt 

 males as already described ; some of these would be difiicult to distinguish 

 from 0. cJiiliensis. 



The species now described, 0. miranda, appears to belong to that sec- 

 tion of the genus containing 0. mediterransa, 0. gammarellns, 0. chiliensis, &c., 



* I am assuming that the numerous females sent with the equally numerous males 

 belong to 0. miranda, for, with one exception, all the recognizable males belong to that 

 species, and I am unable to divide the females into two groups. The one exception 

 i?, however, a fully developed male of 0. chiliensis M.-E., so that possibly some or all 

 of the females may belong to that species. In the meantime I am unable to give any 

 oharacfcers that would differentiate between the females of these two species. 



