GAMMARIDEAN AMPHIPODA 15 



dibiilar palp of A. sfehhlngi is characteristic of all male argissids, as 

 the siibterminal male at hand has a palp which is intermediate between 

 that of A. hamatipes ( ? female) and that of A. stehhingfL (2) The an- 

 terior cephalic crest becomes larger with increased age or with an 

 increase in body size. (3) The long second article of the accessory 

 flagellnm of male A. steJbhingi also is a result of terminal diiferentia- 

 tion. (4) Coxa 3 may vary infraspecifically. (5) The absence of 

 eyes is of no specific value. 



Material. — Station 7229, male, 4.7 mm. 



Distribution. — Subarctic to warm temperate in the northern 

 hemisphere, 4-1096 m; material at hand from minimum depth of 

 1720 m; A. stehbingl recorded from northeastern Atlantic Ocean in a 

 depth of about 940 m. 



Eusiridae 



Rhachotropis Smith 

 Rhachotropis ?cervus J. L. Barnard 



? RJiachotropis cervus J. L. Barnard, 1057a, pp. 16-17, pi. 3 



These specimens have the aspect of Rhachotropis cervus but lack 

 the poorly developed carinal tooth of pleonite 4, and thus they re- 

 semble R. elegans Bonnier (1896), a species that has been considered 

 to be a synonym of R. grimaMii Chevreux (1900). Chevreux' figure 

 of R. grimald'd shows a dorsal carina terminating obtusely on the pos- 

 terior half of pleonite 4. Bonnier's figure shows little evidence of the 

 carina. Both R. elegans and R. grimald'd differ from R. cervus and 

 the material at hand, however, in the absence of a posterolateral tooth 

 on pereonite 7 dorsal to coxa 7. Rhachotropis cervus also has a fourth 

 coxa that is broader than the third and is slightly extended and pro- 

 duced posteriorly. Rhachotropis grimaldii has a symmetrical fourth 

 coxa, which is no broader than coxa 3. Rhachotropis elegans has a 

 fourth coxa similar to that of R. cervus but it is scarcely broader than 

 coxa 3. All coxae of j^. cervus are larger than those described for R. 

 elegans^ and the material at hand is intermediate between R. cervus 

 and R. elegans in the size of all coxae and the width of coxa 4. The 

 lateral cephalic lobes are not clear in eitlier R. grimaldii or R. elegans. 

 Various other small differences are noticeable among the three species 

 in the second articles of pereopods 3 and 5, coxa 1, the posterolateral 

 margin of pleonite 4 above the insertion of uropod 1, and the accessory 

 flagellum. All are characters that should be studied when reexamina- 

 tion of R. grimaldii and R. elegans can be made. 



