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



joints, while the second row appears to be attached along the inner margin itself ; the 

 penultimate joint is swollen and pear-shaped, broader at the base than above ; along the 

 inner margin are some fifteen pairs of long cylindrical spines, which are of a rather 

 unusual form ; the distal third bears two rows of short cyhndrical branches ; the centre 

 of the spine appears to be hollow at the base, and the bounding membrane is continued 

 above into a solid axial rod, which projects for a short way beyond the anterior extremity 

 of the spine. This appendage and the peculiar spines upon the penultimate joint are 

 figured by Grube (loc. cit., pi. v. figs. 3, 3, a), Grube also states that the spines upon 

 this pair of appendages are alike in both males and females : — " Der Innenrand des 2**° 

 Paares Greiffusse tragt lange an der Vorderseite gesagte Stacheln, sowohl beim Mannchen 

 als beim Weibchen." They are in reality quite different in the female ; the fourth joint 

 bears a row of spines arranged in pairs ; on the distal half of the joint these spines are 

 strong and serrated along both margins, resembling entirely the serrated spines found 

 upon the other thoracic limbs ; posteriorly the serrations become less marked, and the 

 proximal end of the joint has only smooth sword-like spines, the third and fourth joints 

 have none of the soft plumose hairs that are found in the males ; their place is occupied 

 by tufts of strong spines, some of which are serrated. In this as in all other species in 

 which the males have the peculiarity here desci'ibed, the females are invariably different, 

 the third pair of thoracic appendages being in this respect closely similar to the succeeding 

 appendages. 



The remaining thoracic appendages are not in any way remarkable. The second joint, 

 which is rather smaller than the first joint, is furnished with a tuft of long hairs upon the 

 inner surface at the distal extremity, among which are a few serrated spines ; the succeed- 

 ing joints, which are approximately of this arm length, the fourth being rather the longest, 

 have a tuft of hairs in the same position, among which are a greater number of serrated 

 spines ; in the penultimate joint the long delicate hairs are almost entirely absent, their 

 place being taken by stout spines, many of which are serrated. Along the outer margin 

 of the joints, with the exception of the first, are tufts of short spines, very few of which are 

 serrated. 



The three anterior abdominal appendages, like those of Serolis schythei, have no 

 plumose hairs upon the basal joint. 



The suture of the operculum is oblique. 



The exopodite of the fifth pair of abdominal appendages is bifurcate. 



Station 316, February 3, 1876 ; lat. 51° 32' S., long. 58° 6' W.; 4 fathoms; bottom, 

 mud. 



