34-1- AMPIIIPODA NORM ALIA. 



3. RHABDOSOMA. 



Rhabdosonm, JJlit'fr, Sir E. livlclicrs Voi/tii/c of the Smnaranrj, p. 63. 

 MacroL'i'plialus, Sjmicc Jiate, Ann. Nat. Hint, ^rd .ser. i. p. 3U2. 



Animal long and slender. Cophalon produced anteriorly into a long- 

 rostrum, narrowed behind the eyes. Pleon hanng the three an- 

 terior segments normal ; the fourth and fifth fused into one, long, 

 cylindrical, narrow ; sixth long, cylindrical, narrow. Superior 

 antcnnix! in front of the eyes, short ; inferior antennae folded be- 

 neath the cephalon. Gnathopoda short, complexly chelate. Pe- 

 reiopoda not having the basa dilated. Three posterior paii's of 

 pleopoda biramous. Telson cylindrical, long. 



This genus is incorporated with Oxycephalus by M. -Edwards. 



1. Rhabdosoma armatum. (Plate LIV. fig. 6.) 



Rhabdosoma armatum, Tlliite, SirE. Belcher'' s Voyage of the Samarang, 



p. 03. 

 Oxycephalus avmatus, Edwards, Hist, des Crust, iii. p. 101. 

 Macrocephalus longirostris, Spettce Bate, Ann. Nat. Hist. 3rd ser. i. 



p. 362. 



Female. — Cephalon as long as the animal ; rostrum five times as long 

 as the rest of the cephalon. Second and thii'd segments of the plcon 

 postero-dorsally produced into a point ; fourth and fifth segments 

 fused together; sixth segment nearly as long again as the preceding. 

 Superior antenna) terminating in a long-oval flat joint ; inferior 

 antennae obsolete. First pair of gnathopoda ha\ing the carpus 

 infero-anteriorly produced beyond the extremity of the jiropodos, 

 and furnished with a single long tooth upon the inferior margin ; 

 propodos two -thirds as broad as long, and having the inferior 

 angle anteriorly produced ; dactylos short, sharp, and capable of 

 antagonizing at the apex with the produced extremities of the 

 propodos and carpus. Second pair of gnathopoda resembling the 

 first, but much longer and larger, having the inferior angle of the 

 carpus produced considerably longer than the propodos ; dactylos 

 long, capable of antagonizing at the apex against that of the 

 produced carpus, and near its centre with, the propodos. First 

 two pairs jof pereiopoda subcqual, the second a little the longer ; 

 third pair longer than the preceding; fourth pair one-third 

 shorter than the third ; fifth obsolete. Antepenultimate pair of 

 pleopoda reaching as far as the ultimate, upper margin of pe- 

 dimcle serrated: penultimate pair of pleopoda originating from 

 the posterior extremity of the same segment as the preceding, and 

 not longer than the sixth segment of the plcon : ultimate pair of 

 pleopoda about two-thirds the length of the antepenultimate ; 



