GAMMARIDEAN AMPHIPODA 53 



described: Aristias toi)senti Clievreux (1900), J., mlcrops Sars (1895), 

 A. falcatus Stephensen (1923) and A. adrogans J. L. Barnard (1964d) . 

 In characters other than the telson, A. expers difi'ers from these as 

 follows: from A. topsentl by the weak development of the wmg-like 

 ridges of urosomite 3; from A. micro ps by the subacutely and more 

 strongly produced lateral cephalic lobes; from A. falcatus by the 

 narrower distal end of article 6 of gnathopod 2 and the poor develop- 

 ment of spination on the inner rami of uropods 1 and 2; and from A. 

 adrogans by the poor spination of the uropods and the larger uro- 

 somite 3. The new species and A. adrogans^ both Pacific species, seem 

 most closely related. 



Aristias expers reseml^les three oculate species. It differs from its 

 sympatriot Aristias veleronis Hurley (1963) by the shortness of the 

 stenopodous portion of pereopod 5, the stouter gnathopod 1, and the 

 apparent absence of small cusps on the pleonal epimera. It differs 

 from A. japonicus Gurjanova (19G2) primarily by the shorter inner 

 ramus of uropod 3 and the small size of the spines of the telson. It 

 differs from A. antarcticus Walker (see 1907) by the stoutness of the 

 first gnathopod, the elongated accessory flagellum and the small size 

 of the dactyl of gnathopod 2. 



The first maxillary palp of A. expers superficially appears to be 

 uniarticulate, the division between articles 1 and 2 being nearly ob- 

 fuscated. As in other species of Aristias the inner and outer plates 

 of maxilla 1 of ^1. expers are not as divergent as in A. neglectus 

 Hansen (see Sars, 1895, pi. 17, fig. 2). 



Aristiopsis J. L. Barnard 



Aristiopsis tacita J. L. Barnard 



Figure 22 



Aristiopsis tacitus J. L. Barnard, 19G1, p. 31, fig. 2. 



This species, described from the Tasman Sea, is now demonstrated 

 to be of widespread occurrence in the Pacific Ocean. The specimen 

 at hand differs in no significant character from that originally de- 

 scribed, except in the slightly different shape and stronger setae of 

 article 2 on pereopod 5. Some of the mouthparts are illustrated in 

 finer detail than before. Apparently uropod 2 was erroneously de- 

 scribed and figured because it is the inner and not the outer ramus 

 that has the dorsal constriction on the specimen at hand. The append- 

 age as shown on the body was incorrectly rendered by Barnard (19G1) , 

 although one may see on the enlarged version that it is the inner and 

 not the outer ramus w^hich is constricted because the major peduncular 



