systematic report «7 



Occurrence : 



St. 1578. 26. iv. 35 (night). Midway between Comoro Is. and African coast, 500-0 m., 1 adult ?, with large empty 



brood pouch, 9-8 mm. 

 St. 1585. 1. v. 35 (night). Indian Ocean, north-west of Seychelles, 500-0 m., 1 $, 8-8 mm., 1 juv. $. 

 St. 1586. 2. v. 35 (night). Midway between Seychelles and Obbia, 550-0 m., 2 adult SS, 9-5 mm. 



Distribution. An oceanic species widely distributed in the upper and surface waters of the 

 tropical regions of the Pacific and Indian Oceans from the Arabian Sea to the east of China. 



Subfamily Rhopalophthalminae 

 Genus Rhopalophthalmus Illig, 1906 

 1906a Rhopalophthalmus Illig, p. 207. 



Remarks. This genus closely resembles Gastrosaccas but may be distinguished from it by the 

 absence of spines arming the outer margin of the exopod of the uropod, by the dimorphism of the 

 reduced endopod of the eighth thoracic appendage, by the absence of a cleft in the telson and by the 

 absence of pleural plates on the first abdominal somite of the female. In recording R. egregius from 

 South African waters (1952, p. 161) I drew attention to the fact that pleural plates were present on the 

 first abdominal somite of the males of both the known species of Rhopalophthalmus and, since the 

 males in the Discovery collections show the same character, I consider that it can be regarded as of 

 generic significance. 



Of the two known species of the genus only one, R. egregius, is present in the Discovery collections. 



Rhopalophthalmus egregius Hansen, 19 10 



1910 Rhopalophthalmus egregius Hansen, pp. 48-50, figs. 

 191 5 Rhopalophthalmus egregius, Tattersall, p. 151. 



Occurrence: 



St. 149. 10. i. 27 (day). Mouth of Cumberland Bay, South Georgia, 200-234 m., 3 .$$, largest 10-2 mm. 



St. 274. 4. viii. 27 (day). Off St Paul de Loanda, Angola, 65-64 m., about twenty very badly damaged specimens 



and many fragments. This tube had dried up. (Colour note on label, 'Quite transparent except for black eyes 



and a dark red median spot at base of telson'.) 

 St. 279. 10. viii. 27 (day). Off Cape Lopez, French Congo, 58-67 m., 1 adult ?, 10 mm. 



Remarks. This species can be distinguished from the only other species of the genus, R. flagellipes, 

 by the shorter, more robust eyes and by the presence of a very strong spine on the endopod of the 

 uropod at the distal end of the statocyst. 



Distribution. The species is widely distributed in the shallow coastal waters of the Pacific and 

 Indian Oceans, and has been recorded from the Great Barrier Reef and New South Wales (Tattersall, 

 1936, p. 147 and 1940, p. 330). It has twice been found in the open ocean, once in the Torres Strait 

 and once near Norfolk Island (Colosi, 1920, p. 237). I have myself recorded it from eight localities 

 from the coasts of South Africa extending from Richard's Bay on the east coast to Langebaan Bay 

 on the west coast (O. S. Tattersall, 1952, p. 161). The three stations at which it was taken by the 

 'Discovery' considerably extend its known geographical range. In particular its occurrence off 

 South Georgia proves that it can inhabit much more southerly waters than was hitherto supposed. 



R. egregius is a euryhaline, eurythermic species living as a rule in swarms at or very near the bottom. 

 It has usually been taken in large numbers in brackish waters of very low salinity which are subject to 

 a considerable range of temperature and it now appears to be widely distributed in the South Atlantic 

 as well as the Indian and Pacific Oceans. 



