146 THE VOYAGE OF H.M.S. CHALLENGER. 



40. Stylocheiron elongatum, G. O. Sars (PL XXVII. figs. 6-10). 



Stijhidieiron ehuKjatam, G. 0. Sars, Preliminary Notices on the Challenger Schizopoda, No. 38. 



SpecijiG Characters. — Form of body very slender and elougate. Carapace somewhat 

 gibbous in anterior part; rostral projection very short. Last caudal segment remarkably 

 elongate, exceeding in length the two preceding taken together. Eyes rather large and 

 compressed, cornea olilong, n(3t contracted in upper part. Antennular peduncle nearly as 

 long as carapace, the two outer joints subequal and but slightly dilated in male. 

 Antennal scale rather narrow, apex obliquely tapering to a projecting corner. Second 

 pair of legs rather shorter than body, meral joint longer than carpal, hand nearly as in 

 the two last species. Inner plate of uropoda much longer than outer. Length of adult 

 male 13 mm. 



Remarks. — The present species is recognised at once by the very slender form of the 

 body, and, more particularly, the great length of the last caudal segment. Moreover, 

 the deviating form of the antennal scale, as also the comparatively less elongate second 

 pair of legs, afford good specific characters. 



Description. — Two specimens only of this distinct form were found in the collection, 

 one an adult male, the other a young female. The length of the male specimen is 13 mm. 



The form of the l)ody (see PL XXVII. fig. 6) is more slender and elongate by far than 

 in any of the other species, the tail in particular being greatly produced. 



The carapace is comparatively short, measuring in length not more than a third of 

 the tail, and would appear to be somewhat gibbous throughout its anterior part, with a 

 somewhat short and low crest above in the middle. The rostral projection is very 

 short, reaching but slightly beyond the ocular segment. The antero-lateral corners of 

 the carapace are rather produced, and very acute. 



The caudal segments taper gradually from before backwards, and are furnished with 

 comparatively small, rounded epimera. The last segment is remarkably elongate and 

 slender, exceeding even the two preceding ones taken together, and would appear to lack 

 the preanal spine. 



The eyes are rather large, and expanded toward the apex, but decidedly compressed, 

 with the cornea narrow oblong, and of nearly uniform breadth throughout. 



The antennular peduncle in the female specimen is very slender and elongate ; that of 

 tbe male is comparatively more thickset, with the two outer joints somewhat less narrow 

 and about equal in length. The flagella were broken ofi" in both specimens. 



The antennal scale (fig. 7) is not very elongate, reaching but slightly (in the male) 

 beyond the second joint of the antennular peduncle, and exhibits a form somewhat 

 dissimilar to that in the other species, being broadest in the middle and tapering 

 gradnnlly towards the apex, which is not truncate, but ends in a projecting corner. The 



