1884.] DURING THE VOYAGE OF H.M.S. 'CHALLENGER.' 335 



respects the two sexes do not differ, except of coarse in the form of 

 the second thoracic and second abdominal appendages. 



The form of the body is regularly oval, and the epimera overlap 

 each other closely and do not project freely except the sixth pair, 

 which project some way beyond the two last pairs. 



The dorsal surface of the body is entirely covered with small 

 rounded tubercles, and the posterior margin of each segment is 

 occupied by a series of rather larger tubercles ; in the middle of the 

 posterior margin of each segment, including the cephalic shield, is a 

 short backwardly directed spine. As in 8. longicaudata, the sutures 

 separating the fifth thoracic from the sixth and the sixth from the 

 first abdominal are incomplete in the middle line. 



The caudal shield is irregularly triangular in outline, it has a slight 

 carina. About the middle a row of rather larger tubercles crosses 

 the carina at right angles ; one of these tubercles on each side, close to 

 the lateral margin of the caudal shield, is conspicuously large. 



The middle portion of the scuta of the three free abdominal 

 segments is prolonged into a spine, that of the first abdominal 

 segment being by far the larger. 



Both pairs of antennae are of about the same length. 



Station 162, 38 fathoms. 



6. Serolis elongata, n. sp. 



This species in its general configuration is not unlike Serolis 

 australiensis, and it is very possible that the examination of a large 

 series of specimens would prove that the two are identical. In the 

 meantime, however, the single specimen contained in the 'Challenger' 

 collection is sufficiently different to warrant its separation as a 

 distinct species. 



The specimen, which has the characters of a female, measures 10 

 millim. in length by 6 millim. in breadth. The surface of the body 

 is not so much covered with tubercles as in Serolis australiensis ; the 

 posterior margin of the cephalic shield and the free segments of the 

 body, except the first, is prolonged into a stout hook-like spine, and 

 the thoracic segments have a line of short tubercles on either side of 

 the central spine. 



The caudal shield is keeled ; a row of tubercles runs across it at 

 right angles, the outermost one on each side being the largest ; 

 another row of tubercles traverses the lateral margin of the caudal 

 shield. 



Station 163a, 30 fathoms. 



7. Serolis pallida, n. sp. 



The ' Challenger ' obtained two specimens of this species, one a 

 male and the other a female. 



The female is the larger, measuring 16 millim. in length and 13 

 millim. in breadth, while the male is only 9 millim. long and 7 

 millim. broad. The body is oval, somewhat pear-shaped from the 

 form of the caudal shield, which narrows rapidly towards the end. 

 All the segments of the body, except the first, fifth, and sixth, are 



23* 



