I7 2 DISCOVERY REPORTS 



The simplest development is seen in the northern cornigera, where the hind margin 

 of the 2nd joint in peraeopods 3 and 4 is channelled, the channel being bounded by a 

 keel or flange on the outer and inner sides. These keels diverge right from the base of 

 the joint, and continue separate to the end, where the outer one is expanded into a lobe. 

 On peraeopod 4 the inner keel is slightly expanded. On peraeopod 5 it is always the outer 

 keel which is variously expanded, and we need not consider this peraeopod any further. 



All three peraeopods have a longitudinal keel in the middle of the outer surface of 

 the 2nd joint, and the 3rd joint also possesses an outer and inner flange on the hind 

 margin for the reception of the 4th joint when the limb is flexed. 



In the Antarctic forms we find several modifications of the simple channel of cornigera. 

 In explanation of the figures here given (Fig. 104) of all the species in the present 

 collection, it will suffice to point out how important it is in descriptions to distinguish 

 the point of divergence of the outer and inner keels, which keel is expanded, and the 

 course of the lateral longitudinal keel. 



Epimeria macrodonta, Wlkr. (Fig. 105). 



Walker, 1907, p. 24, pi. viii, fig. 14. 



Chevreux, 1913, p. 148 and p. 149, figs. 41-43 (similis). 



Schellenberg, 1926, p. 343. 



Barnard, 1930, p. 372. 



forma macrodonta, Wlkr. 



Occurrence: St. 181. Palmer Archipelago. 1 juv. 10 mm. 



forma similis, Chevr. 



Occurrence: 1. St. 170. South Shetlands. 19 SS 12-22 mm., 16 $$ 15-34 mm -> 8 ovi g- ?? 2 §- 

 32 mm., 2 ?$ with embryos 33 mm. 



2. St. 175. South Shetlands. 2 c?c? 12 and 30 mm. 



3. St. 181. Palmer Archipelago. 1 ? $ 14 mm. 



4. St. 182. Palmer Archipelago. 1 £ 18 mm., 1 juv. 6-5 mm. 



Fig. 105. Epimeria macrodonla, Wlkr. Photograph 

 taken on board (St. 175). 



