GAMMARIDEAN AMPHIPODA 21 



posterior portion of ventral margin with deep excavation defined by 

 sharp cusp ; coxae '2 and 3 not acuminate, coxa 4 nearly as long as wide, 

 scarcely excavate posteriorly, posteroventral corner rounded, coxa 7 

 witli posteroventral hooklike cusp; article 2 of gnathopod 1 lacking 

 medial spine row, lobe of article 5 on gnathopod 2 more slender than on 

 gnathopod 1 ; second articles of pereopods 3 and 4 linear, of pereopod 

 5 very slender for the genus, posterodistal corner simple, rounded; 

 pereonite 7 lacking dorsal tooth, posterolateral corner slightly pro- 

 duced ventrally ; pleonites 1-3 tricuspidate, lateral teeth lacking cari- 

 nae, pleonites 4 and 5 dorsally simple, posterolaterally with small 

 processes above insertions of uropods; pleonal epimera 1 and 2 

 posteroventrally rounded, epimeron 3 with ventroposterior portion 

 convex, posteroventral corner with small tooth and notch, otherwise 

 unserrated; telson cleft nearly halfway. 



HoLOTYPE. — AHF No. 6031, ?sex, 3.8 nnn. Unique. 



Type-locality.— Station 7229, 27°54'25" N, 116°40'00" W, 1720- 

 1748 m, Dec. 31, 1960. 



Relationship. — This species has affinities with Eharhofropis gri- 

 malclil (see Chevreux, 1900), from the north Atlantic Ocean, because 

 of a dorsally tricuspidate pleonite 3, the absence of a dorsal tooth from 

 pleonite 4, the absence of a dorsal tooth from pereonite 7 and the 

 deeply cleft telson. Rhachotropis elegans Bonnier (1896) has been 

 considered to be a synonym of R. grimaldil and the species at hand 

 resembles the figures of R. elegans in its lack of a dorsal crest on 

 pleonite 4, which is shown to occur on R. grhnaldli by Chevreux 

 (1900). Rhachotropis m/ultesimus differs from R. grhnaldli and R. 

 elegans by the absence of serrations on pleonal epimeron 3, by the 

 deeply excavate and posteriorly hooked ventral margin of coxa 1, and 

 Ijy the slender second article of pereopod 5. The new species resembles 

 R. cervus J. L. Barnard (1957a), from bathyal southern California, 

 but the latter has a distinct, although small, tooth on pleonite 4, a 

 broadly expanded article 2 of pereopod 5, an elongated mandibular 

 [)al[) article 3, an acute rostrum, a poorly excavate coxa 1 and other 

 minor differences. The Arctic-North Atlantic Rliacliotropis oculatus 

 (Hansen) has eyes, serrate third pleonal epimeron, a minute dorsal 

 tooth on pereonite 7 and unexcavate coxa 1. 



Haustoriidae 



Vrothoides Stebbiiig 



Vrothokles Stebbing, 1891, p. 2(>. 



Diagnosis (revised). — Rostrum well developed, broad, flat, turned 

 downwards and tucked between antennae; body short, setose, legs 



