970 ON CHUSTACEAN8 OF THE GENUS SEKOEBTES. [Dec. 1, 



ooiDinon at the surface, but Ortmann communicates that it has 

 been captured in the intermediate net from 700-500 m.; and if 

 some of the specimens recorded by Bate (p. 390) as 38, 43, and 50 

 mm. long, and coming respectively from 600, 2150, and 345 fathoms, 

 really belong to this species, it grows considerably larger in the 

 deep sea, as no specimen from the surface exceeds 30 mm. Finally, 

 S. cornutus, Kr., and *^. edwardsi, Kr., are the only instances of 

 the 14 species which only have been captured at the surface (aiid 

 in vertical nets drawn up from 500 m. to tlie surface). In this 

 paper I have described the mature forms of S. vigilax, Stimps., 

 H. J. H., S. penerinhi. Bate, H. J. H., and S. incertus, n. sp., 

 which have all been captured at the surface. S. tenuiremis, Kr., 

 H. J. H., and S. corniculum, Kr., II. J. H., are common at the 

 surface in the Mastigo2yus-sta,ges ; above I have described the 

 younger black-eyed forms of both species, also captured at the 

 surface, but the adult stages are quite unknown and must, in 

 my opinion, be true deep-sea forms. Of S. diapontius, Bate, and 

 S. mediferraneus, to., only the Mastigopits-forma are known, and 

 the adults are certainly inhabitants of the depths. (S. profundus, 

 Bate, from 1375 and 2550 fathoms, I omit, as the species is too 

 uncertain.) 



Though we still know too little of the bathymetrical distribution, 

 it must, I think, be taken as proved that at least two-tidrds of the 

 species inhabit the depths of the sea when the animals have quite 

 ai-rived at maturity (or at least at their full length, cfr. S. atlantieus). 

 1 can say that with two exceptions — my single adult specimen of 

 S. incertus, m., and Kroyer's specimen of S. arcticus, Kr., — no 

 specimen exceeding 30 mm. in length recorded in the existing 

 literature or seen by me has been captured near the surface, but all 

 large specimens, from 30 mm. to 113 mm. {S. inous. Fax.) in length, 

 have been secured with trawl or dredge coming from a considerable 

 to a very great depth (345-2574 fath.). Faxon writes on p. 240 : 

 " There can be no doubt that the deep-sea Crustacea occasionally 

 come to, or very near to, the surface," and he communicates 

 several instances ; I think that, for instance, my single and large 

 specimen of *S. incertus, m., 47 mm. long, has been secured on such 

 a visit. It is evident that the animals as true swimming forms do 

 not live on the bottom itself, but, I presume, in the water- 

 stratum just above it. 



As will be seen from this paper, our knowledge of this rich and 

 curious genus is still rather imperfect. A good monograph, based 

 on the study of the collections in the seven or eight museums which 

 possess materials of importance, would be extremely valuable 

 and elicit numerous new facts ; and future deep-sea expeditions, 

 making use of the trawl, intermediate net, vertical net, and surface 

 net, would be sure to discover new species and especially enlarge 

 our knowledge of the metamorphosis and distribution. 



