158 DISCOVERY REPORTS 



nerve cord which may be seen folded below the alimentary canal (Text-fig. 6 b). All signs of the 



reproductive system have disappeared except for the posterior ends of the oviducts. 



The posterior opening of the pouch, extending transversely immediately behind the free distal 

 portions of the fourth pair of plates, is protected by a fold of the posterior wall of the pouch. This fold 

 is double and is directed forwards to cover about three-quarters of the free surface of the plates ; only 

 the middle portion of the wall is involved, resulting in the formation of a pair of lateral diverticula to 

 the pouch (Text-fig. ya, c). The ventral portion of the fold is somewhat thickened and presumably 

 acts as a valve, closing the opening and preventing the escape of eggs and developing young. The 

 anterior opening of the pouch, which is much smaller, is protected by the coxal lobes which are 

 developed on the coxae of the maxillipeds. Some idea of the size of the pouch may be gathered from 

 the fact that a breeding female, measuring only 7 mm. in length, and 4 mm. in greatest breadth, 

 contained 24 young specimens which varied in length from 1-5 to 2 mm. 



The significance of these modifications of the brood pouch cannot be discussed without some 

 reference to the habits of the species concerned. The only clue — if it can be called such — lies in the 

 fact that they all appear to live in a ' dirty ' environment, their bodies being invariably covered with 

 particles of different types. This mode of life would expose the young, developing in a comparatively 

 soft ventrally directed pouch, to serious damage, either by actual contact with the surroundings, or 

 by infiltration of particles into the marsupium itself. The two kinds of brood pouch met with 

 in E. oculopetiolata and E. ociilata obviously afford greater protection than does the typical form of 

 pouch. 



Edotia bilobata Nordenstam, 1933 (Text-fig. d,a-e) 



Edotia bilobata Nordenstam, 1933, pp. 98-100, pi. i, fig. 6; text-figs. 23c, 2/^a-c. 



Occurrence. WS 245 : 18. vii. 28, 52° 36' 00" S., 63° 40' 00" W., 304-290 m., i S- WS 871 ; i. iv. 32, 53" 16' 00" S., 

 64° 12' W., 336-341 m., I ?. 



Remarks. This species was instituted by Nordenstam (1933) from examination of a single immature 

 specimen. The Discovery collections contain two specimens, an adult male measuring 7-8 mm. in 

 length and 3 mm. in greatest breadth, and a breeding female, measuring 10 mm. in length and 

 3-5 mm. in breadth. 



These specimens agree with the description given by Nordenstam except for the coxal plates of the 

 anterior thoracic somites; this point has already been discussed (p. 154) in the introduction to the 

 genus. Before passing on to the consideration of certain details, the general hairiness of the body and 

 its appendages is worth noting. The detailed structure of the antennules and antennae cannot be seen 

 in the figure given by Nordenstam. The sensory setae present on the flagellum of the antennule are 

 more numerous in the male than in the female ; in the latter they are six in number and occur near the 

 distal extremity. The arrangement in the male is shown in Text-fig. 8rf, and the structure of the 

 antenna in Text-fig. 8 c. 



Except for the maxillipeds Nordenstam makes no mention of the form of the thoracic appendages. 

 The second pair of pereiopods (Text-fig. 8 ft) is shorter than the remaining ones, but all have the 

 propodus somewhat dilated to form, with the dactylus, a prehensile limb. The remaining six pairs are 

 all very similar in structure (Text-fig. 80). 



The brood pouch of the breeding female is of the modified type described in the introduction to the 

 genus (pp. 154-155)- 



In the male, the penis is single, very broad and distally cleft ; its base lies in a shallow depression 

 on the front margin of the first abdominal segment ; the form and position of the penis bears a close 

 resemblance to that of E. oculata (Text-fig. ib). The appendix masculina is shown in Text-fig. 8e. 



