GAMMARIDEAN AMPHIPODA 167 



1 also are characteristic of several s[)ecios of P,scu<lotiron but never of 

 I'lron. 



Pseud of iron eoas lias its closest affinities with the type-species, P. 

 houvierl Chevrenx, which has the characteristic L-shaped coxa 4 ; but, 

 which unlike other members of Pseudofh'07i, has shortened first anten- 

 nal peduncles. The resemblance between the two species occurs in 

 the shape of the head and the short, complexly ornamented clawlike 

 pereopodal dactyls. Other species of Pscvdot'tron have elongated, 

 simple pereopodal dactyls, but various species of Tiroii, such as the 

 type-species, T. spiniferum (Stimpson) and 7'. hiocellafuni J. L. Bar- 

 nard (1962b) have short, clawlike, partially ornamented dactyls, thus 

 representing another case of character-mixing among species of the 

 two genera. 



EemarivS. — A benthic feeding habit is indicated for the specimen at 

 hand in view of the mineral particles occurring in the alimentary tract. 

 Theceplialic shapes of various members of Pseudofhon may be adapta- 

 tions connected with rooting or ploughing in very fine sediments, the 

 streamlined and elongated antennae being locked oblicpiely posterior- 

 wards in the lateral cephalic channels during the process. Shallow- 

 water syno})iids with massive, unstreamlined heads may be adapted for 

 rooting in coarse sediments. 



Pseudotiron longicaudatus greteiis, new subspecies 



Figures S2, S3 



Diagnosis. — Head strongly arched forward, v.ith antenna 1 attached 

 very much posterior to frontal cephalic process, no distinct rostrum, 

 with a notch on margin near insertion of antenna 1, small epistomal 

 protrusion nearly hidden by lateral cephalic lobe occurring below 

 notch; eyes absent; upper lip with small, blunt anterior ])rocess; coxa 

 1 small (relative to P. goJenH J. L. Barnard 10G2a), coxa 3 short and 

 truncate posteriorly (compared with /''. /. longicaudatus)^ coxa 4 small 

 (compared with P. golens) ; dactyls of gnathopods very long, lanceo- 

 late (compared with P. hoiivieri) ; pleonal epimeron 1 with rounded 

 posteroventral corner, epimera 2 and 3 slightly convex posteriorly, 

 with poorly developed tooth at each ])Osteroventral corner; dorsal 

 margins of pleonites 1-3 sparsely sen-ate, two serrations on ]iereonite 

 7; pleonito 4 scarcely produced, 5 with long dorsal tooth; mouthparts 

 like P. /. longiccmdafvH Pirlot (1034) but with slight vai-iations in 

 numl)ers of setae probably owing to age diil'erence in specimens 

 analyzed. 



HoLOTYPE. — AHF Xo. G024, male 7.0 mm. 



