48 

 21. Benthcsicymus Bartlctti, S. I. Smith. 



Bentheticymus n<irlletti, S. I. Smith, Bull. Mus. Comp. Zool. X. 1881-82, p. 82, \>\. xiv. figs. 1-7. 



Bentlwecttes Bartletti, 8. I. Smith, Albatrogg Crust, in Eep. U. 8. Fish. Corom. for 1882, j>. 3:il, pi. i. fig. 8, 

 and for 1885, p. 87, pi. xviii. figs. 2, a-b, uml 1'roc. U. 8. Nat. MIIH. 1880, p. 6U8: A. Agagsiz, Bull. Mas. Comp. 

 Zool. XV. 1888, p. 47, fig. 248. 



So far as the male is concerned this species closely resembles B. iwoettigatoris, 

 from which it differs only in the following particulars : 



(1) the rostrum has only 2 teeth on its dorsal edge : 



(2) only the 5th and 6th abdominal terga are carinated, and the carina of 

 the 5th is armed with a long hooked spine : 



(3) the curved and truncated dactylus of the external maxillipeds has 

 several spines, which are placed at its tip and along it outer edge : 



(4) the vertical tooth on the 1st abdominal sternum is even larger. 

 Bay of Bengal, off the north-eastern coast of Ceylon, 771-665 fathoms. 



Regd. No. 2. 



GENNADAS, Spence Bate. 



Gennadas, Spence Bate, Ann. Mag. Nat. Hist., Sept. 1881, p. 101 : I'lmllriiger CruBtacea Macrura, p. 33!. 

 Amalopenietts, S. I. Smith, Bull. Mus. Comp. Zool. X. 1881-82, p. 86. 



Differs from Benthesicym/us only in the following particulars : 



(1) the exopodites of the 2nd maxillipeds are only about as long as the 

 endopodites, and the endopodites have a thin broad foliaceous oval merus beneath 

 which the 3 terminal joints are concealed in flexion : 



(2) the ischium and merus of the external maxillipeds are also thin broad 

 and subfoliaceous : 



(3) the ischium merus and carpus of the 1st pair of legs are thin broad and 

 compressed : 



(4) the pleurobranohwe though by no means rudimentary are considerably 

 reduced in size. 



It is doubtful whether it would not be better to regard Gennadas as a 

 subgenus of Bemthesieymua, 



j flic Lidi'in N^in-ii x i if CJenuadasi. 



1. The 3rd-6th abdominal terga are carinated : the exopodites of the 1st 

 pair of abdominal appendages are longer than the carapace (and 

 rostrum) ... ... ... ... ... Gicarinahts. 



II. Only the 6th abdominal tergum is carinated : the exopodites of the 



1st pair of abdominal appendages are shorter than the carapace. ... G. parvtu. 



