50 



increasing in length and thickness to or beyond the middle, where they are very strong; the 

 terminal portion of the spines without any lateral armature. 



Length of both sexes lo mm. 



Remarks. — This species, which shows much resemblance to Siriclla, is one of the 

 most interesting forms of Mysidacea secured by the "Siboga". It may be convenient to remark 

 that the state of preservation did not allow a more detailed description of the distal part of the 

 thoracic legs. — The species is easily distinguished from R. flagellipes Illig (from the estuary 

 of the Congo) by much shorter eye-stalks. 



Subfamily IV. Gastrosaccinse Norm. 



The characters of the subfamily is given in the synopsis on p. ii — 12. The subfamily 

 was established in 1892 by Norman for the genera Gastrosacciis Norm, and Anchialus Kroyer; 

 he saw that these two genera, though differing much as to general aspect, are in reality related 

 to each other. In 1906 the same author substituted the name Anchialuia for Anchialus, which 

 was preoccupied for a genus of Coleoptera. Kossmann in 1880 established the genus Haplostylis, 

 which in my opinion cannot be maintained as well separated irom Gastrosaccit-s-^ the same is 

 the case with Pontoiuysis Czern. established in 1882. Chlamydopkon Ortm., established in 1893, 

 is also to be cancelled, being founded on a species closely allied to Gasfrosacais spinifer Goes. 

 ArchcEomxsis Czern., established in 1S82, is to be maintained, because the pleopods of the 

 female, though very small, are all biramous ; the genus is nearly related to Gastrosacciis. The 

 genus Callomysls, established by Holmes in 1895, is probably identical with Archceoniysis, 

 having the "pleopods in the female rudimentary but biramous"; Holmes described and figured 

 the exopod of the uropods as setose along the outer margin, but I suppose it to be an error, 

 as that margin probably is furnished with a row of feebly curved spines as in Gastrosacciis and 

 Archcsomysis. In the following I establish two new genera, Paranchialina and P scudanchialina , 

 on two species described by G. O. Sars in his "Challenger" work and by him referred to 

 Anchialus \ the genera Anchialina, Gastrosacciis and Pseudanchialina are represented in the 

 "Siboga" collection. — Probably no other genus established in the literature belongs to the 

 present subfamily. 



Anchialina Norman. 

 [Anclnaliis Kr., preoccupied). 



Description. — Body stout. Carapace long, covering the thorax at most with the 

 exception of the posterior half of its last segment ; posterior margin straight or feebly emarginate ; 

 frontal plate somewhat or very much produced. Eyes well developed; eye-stalks somewhat 

 short. Antennular peduncle much thicker in the male than in the female; the male lobe short, 

 tuberculiform ; outer flagellum in the male much expanded at the base. Antennal squama small, 

 short; its outer margin naked and terminating in a denticle; second joint of the endopod very 

 much longer and thicker in the male than in the female (PL VII, figs, -^c — 3^/). Mandibles with 



