954 DB. H. J. HiNSEN ON CnrSTACEANB [Dec. 1, 



specimens, the one determined by Chun, the other by Ortmann, are 

 referred by these authors to the same species. 



S. cornutus, Kr., and especially S. lonc/ispinus. Bate, present 

 some affinity to S. edwardsi, Kr., and allied species, which becomes 

 very evident by the fact that a short process is found on the outer 

 side of the third joint of trl.' and trl.* 



Of S. inous, Yax., I iiave seen no specimens. 



A. b. j3. 1. Of S. rohustus. Smith, *bf. japonicus, Bate {S. mollis, 

 Smith), and S. lisulcatvs, Wood-Mas., I have seen no specimens. 

 Of S. rohtistits we possess several stages of the Mastigopus, but 

 having found none of them described I will omit discussing them 

 in this paper. 



A. h. /3. 2. This rich section of adults and larvoe I have called 

 the arcticus-gcow^, as they are very nearly related to each other, and 

 S. arciicus, Kr., is the only one well described of the mature forms 

 and the sole species of which I am able to trace the whole develop- 

 ment from the Acanthosoma (inch) to the adult. I will begin with 

 some remarks on the adults and on a subadult species. 



S. arcticus, Kr., is well represented by Kriiyer (p. 240, tab. iii. 

 fig. 7, a~g ; tab. v. fig. 16) ; later on 8. I. Smith, in the various 

 papers (see above), communicates some additional notes and good 

 figures. The species has been captured in the Atlantic, northward 

 to Greenland, and southward to lat. 38° S., long. 12° E. (Bf us, 

 Copenh.) ; further, in the Mediterranean near Ischia {S. magnifiais, 

 Chun), and some older larvai in the Adriatic at Eagusa and 

 Lesina (Chun's collection). But, together with these last larva), I 

 found in Chun's colleclion some young specimens and older larva) 

 of a new and unfortunately closely related species, S. mediierra- 

 neiis, n. sp., which makes it necessary to present some remarks on 

 the two species, so that it will be possible to distinguish them 

 from each other. Previously no valid species allied to ^?. arcticus, 

 Kr., was known from the Atlantic or the Mediterranean. 



The largest specimen of S. mediterrancus, m., is 19-5 mm. long, 

 and has almost assumed the adult shape, but the eyes are still not 

 black and therefore their final magnitude cannot be determined. 

 Of characters between this subadult stage and the subadidt and 

 adult S. arcticus, Kr., I have found the following : — S. mediterra- 

 neus is destitute of the hepatic spines and the gastro-hepatic 

 groove ; the supra-ocular spines are quite rudimentary ; the basal 

 joint of the antenn. peduncle is obviously somewhat shorter than 

 the two following taken together, which are a little more coarse 

 than in S. arcticus, while the basal joint from the s))iue near the 

 basis of the exterior margin is somewhat more narrow, with the 

 exterior margin less convex in outline than in S. arcticus ; the ext. 

 br. of urp. is but 4 times longer than broad, with the outer margin 

 beyond the spine strijdngly concave. In S. arcticus, Kr., the 

 supra-ocular and hepatic spines and the gastro-hepatic groove are 

 well developed ; the basal joint of the antenn. ped. is (measured 

 with accuracy) almost or quite as long as the two following taken 

 together ; the ext. br. of urp. is exactly 5 times longer than 



