PLEUSTIDAE 



169 



1-3 carinate, the carina on segments 1 and 2 raised posteriorly into a strong pointed 

 tooth, on segment 3 rounded. Postero-inferior angle of segment 3 shortly pointed. 

 Telson boat-shaped, apex slightly incised, a small subterminal notch on lateral margin. 



Both antennae elongate, slender, flagella multiarticulate. Mouth-parts as in 

 S. malmgreni (Sars, 1895, pi. cxxv, fig. 1), except that the mandible has a rather feeble 

 conical molar, minutely setulose at apex; cutting edge with about 10 teeth, secondary 

 cutting plate in left mandible with about eight teeth, in right mandible bidentate. 



Gnathopods 1 and 2, 2nd joint shallowly channelled in front, outer margin slightly 

 lobed at distal end, 4th with a short sharp spine at lower distal angle, 5th and 6th sub- 

 equal, rather elongate, both setose along lower margins, 5th with two rather stronger 

 spine-setae distally, 6th cylindrical, palm oblique, not defined except by three stout 

 submarginal spines, finger overlapping palm. 



Fig. 102. Austropleustes cuspidatus, Brnrd. a. Gnathopod 1. b. Peraeon segments 6 and 7, and pleon seg- 

 ments 1-4. c, d. Dorsal and lateral views of telson. e. Dorsal view of uropod 3 (inner ramus missing). 



Peraeopods 1 and 2, 5th and 6th joints rather strongly spinose on hind margin, 

 dactyls with a small denticle at base of unguis. Peraeopods 3-5, 2nd joint ovately ex- 

 panded, hind margin shallowly notched, 5th and 6th joints rather strongly spinose on 

 anterior margins, dactyls with denticle as in peraeopods 1 and 2. 



Uropods 1 and 2, peduncle longer than rami in uropod 1, shorter than the rami in 

 uropod 2. Uropod 3, peduncle with upper margin keeled and ending in a short tooth, 

 produced below into a channelled process for the reception of the inner ramus, which is 

 lost in both specimens, but is presumably elongate. 



Remarks. Distinguished from all other Pleustids by the dorsal armature. 



Austropleustes simplex, n.sp. (Fig. 103). 



Occurrence: St. 123. South Georgia. One specimen 8 mm. 



Description. Integument (as preserved) not firm, minutely and regularly shagreened. 

 Rostrum extending scarcely to half-way along 1st joint of antenna 1. Eyes rather large, 

 reniform, yellowish. Postantennal angle of head shortly produced in an acute point. 



