194 REV. T. K. K. STEBBING ON TWO 



Grenus Rhachotkopis, S. T. Smith. 



1871. Triiropis, Boeck, Forh. Selsk. Christiania, 1870, p. 158. 



1883. Rhachotropis, S. I. Smith, Proc. U.S. Nat. Mus. vol. tI. p. 222. 



1906. Rhachotropis, Stebbing, Das Tierreicb, Amph. Gamm., Lieferung 21, pp. 347,729. 



The species here included in the genus differs from its congeners and, so 

 far as known, from the rest of the family, by having the third joint of the 

 mandibular palp much shorter than the second. Also the postero-lateral 

 margins of the third pleon segment cannot well be described in the terms 

 which suit the other species. Nevertheless the whole sum of its characters 

 seems to demand that this form should not, under existing circumstances, be 

 separated from RhacJiotrojns. The telson indeed has only a small apical 

 notch instead of the more or less prolonged slit which is usual, but it shares 

 the character of its telson with M. gracilis, Bonnier, and i?. kergueleni, 

 Stebbing, in both of which, on the other hand, the third joint of the man- 

 dibular palp is greatly elongated. The new form is apparently blind, but so 

 are several other species in this genus. It agrees with a certain number in 

 having a microscopically two-jointed accessory flagellum to the first antenuge, 

 and it should here be noticed that this is the case with R. grimaldii, Chevreux. 

 That author's earlier statement on this point I have adopted in 'Das Tierreich,^ 

 without noticing his clear correction of it in his ' Result. Camp. Monaco,' 

 vol. xvi. p. 69, pi. 9. fig. 1 (1900). In other minute details, as well as in 

 many obvious characters, it will be admitted, I think, that the new species is 

 closely tied to this genus, although marked off from its companions by 

 several striking features of its own. 



Rhachoteopis palporum, sp. n. (Plate 28.) 



Rostrum rather short. Perteon broad, a little hairy and transversely 

 rugose, without teeth or processes, except that the lower hind angles of the 

 seventh segment are produced acutely backward. The anterior angles of the 

 first segment are produced subobtusely forward. The first three pleon seg- 

 ments are large, projecting in seven teeth a-piece, of which the medio-dorsal 

 tooth and the postero-lateral pair are short, the subdorsal pair of great length 

 in the first and second segments. In these segments the pair between the 

 subdorsal and postero-lateral pairs are minute, but in the third segment they 

 are more obvious, while their neighbours are comparatively reduced. The 

 second to the fifth segments show a median carina, the fourth segment 

 having a small lateral pair of teeth and a very small median tooth to the rear 

 between two rounded projections. The first three segments slope forward 

 below the postero-lateral teeth. The side-plates of the perseon are not very 



