Indian Deep-sea Dredging. 279 



The functional branchife are sixteen in number, arranged 

 in two series, an outer and an inner. The outer series con- 

 sists of eleven, namely podobranchia viii., anterior arthro- 

 branchia IX., podobr. IX., anterior artlirobr. x., podobr. x., 

 anterior arthrobr. XI., podobr. xi., anterior arthrobr. xil., 

 anterior arthrobr. Xlll., posterior arthrobr. xrii., pleuro- 

 branchia XIV. ; and the inner series of five, namely posterior 

 arthrobr. viii., posterior arthrobr. ix., posterior arthrobr. x., 

 posterior artlirobr. xi., and posterior arthrobr. xil. The number 

 of functional branchiaj thus corresponds exactly with the 

 description and figures of Duvernoy, while their arrangement 

 differs but slightly therefrom — the difference consisting in 

 posterior arthrobranchia Xii. occupying the last place in the 

 inner series instead of the ninth place in the outer series, as 

 in the typical form. There is but one fully developed and 

 functional pleurobranchia, namely that of somite Xiv., the 

 remaining five being reduced to minute rudimentary plumes 

 of no functional importance. 



Type AristcBUS antennatus, Duvernoy. 



13. Aristceus virilis (Sp. Bate). 



Hemipencnis virilis, Sp. Bate, ' Challenger ' Macriira, 1888, p. 303, 



pi. xliv. tig. 4, (5 . 

 Hemipenaus toinentosus, id. ibid. p. 307, pi. xlix. figs. 2, 3, pi. 1., 5 • 



These two species have been separated by Spence Bate on 

 differences which prove to be sexual. 



The remarkable structure of the base of the inner flagellum 

 of the antennules (which probably forms an apparatus for 

 holding the female, and recalls the structure of the same part 

 in our Metapenceus coniger) and the thickening of the tissues 

 of the outer apex of the antennal scale (of which the remark- 

 able prolongation of the apex of the same part in Aristceopsis 

 Edwardsiana is only an extension) have been indicated by 

 Mr. Spence Bate. 



To the above we may add that the rostrum, which in 



