900 DE. H. J. HANSRN ON CRUSXACEANa [Dec. 1, 



9-6 mm. in length, and the spine is wanting or very small, rarely of 

 moderate size. 



In a specimen 6-2 mm. in length the abdomen has lost its spines, 

 the branchial lamella) to mxp.^ and to trl.'-trl.^ are very large in pro- 

 portion to the branchia, still being small, and above trl.' no brancbia 

 or lamella is developed. In the older stages the eye-stalks are 

 short and the eyes are very large, but in the younger stages — be- 

 tween i-5 mm. and C-5 mm. in length — the eyes are still consider- 

 ably larger ; and in specimens of 4-5-5 mm. in length the rostrum 

 is present as a fine and shorter or longer spine ; and there are short 

 or very short spines on the fourth to sixth abdominal segments. 

 Such a larva, 5 mm. long, is briefly mentioned and figured by Bate 

 (p. 428, pi. Ixv. fig. 4) as Mastic/ojius tenuis. Bate ; the figure shows 

 the characteristic process on the fourth joint of mxp.^ the rostrum 

 is not delineated slender enough. The smallest specimen seen by 

 me is, rostrum not included, c. 2-5 mm. long ; the rostrum is as 

 long as the carapace in the median line and distally furnished with 

 fine spines ; the eyes are of enormous size and the eye-stalks shorter 

 than in the older stages ; the third abdominal segment has a short 

 dorsal spine, the fourth and fifth segments each a very long, the 

 sixth segment a long dorsal spine. 



B. For the following species, all belonging to the edtvardsi- 

 group, I think it convenient to give some introductory remarks, 

 and next to treat the adult animals and the Mastii/opus-iorms 

 separately. 



Of adult animals there have been described only S. edwardsi, 

 Kr., and S. hamifer. Ale. & And., to which /S. halia, Fax., established 

 in 1893, and in 1895 unjustly withdrawn by the same author, must 

 be added. But in our museum I have found 4 species of adult 

 forma and 5 species of larvae, 4 of which most decidedly beloug to 

 the 4 adult forms ; thus an adult form unknown to me must exist. 

 One of the adult species is S. ediuardsi, Kr., but I have not been 

 able to refer any of the three other species to <S. halia. Fax., or 

 S. hamifer. Ale. & And. ; the reasons will be given later on. 



How safely I have been able — though not without a rather pro- 

 tracted investigation — to refer the larvae to the adults will appear 

 from the following case. The old larva) are very easy to separate, 

 and I possessed 5 species but only 3 of the adults. By the exa- 

 mination of the characters of the larvae 1 was induced to 

 re-examine one of the adult species and then it became apparent 

 that it was composed of 2 very closely allied but valid species. 

 Undoubtedly authors have commingled 2-3-4 species in references 

 to S. edwardsi, Kr., and between the limits adopted by Faxon it, 

 as stated above, includes at least 4 species. 



The adult species are all closely related and very similar to each 

 other. They are all characterized by the above-mentioned powerful 

 development of mxp.', which is much longer than any of the trunk- 

 legs ; the 4 proximal joints are much incrassated and especially the 

 thickening of the fourth joint is most conspicuous ; the sixth joint 

 in much shorter than the fifth, both strongly compressed and on 



