358 DISCOVERY REPORTS 



longitudinal carina is present on the dorsal surface, and on either side of this is a 

 lateral serrated carina; between these and the central carina is "a short ridge running 

 obliquely towards the margin of the caudal shield from a point a little below and to 

 one side of the commencement of the central carina". 

 Occurrence. Port Jackson, Sydney, 30 fathoms. 



35. Serolis longicaudata, Beddard. 



S. longicaudata, Beddard, 1884a, p. 336; 18846, p. 72, pi. vii, figs. 8-10, pi. viii, figs. 1,2; Whitelegge, 

 1901, p. 237; Chilton, 1917, pp, 397, 400, fig. II ; Nordenstam, 1933, pp. 92-3. 



Diagnostic characters. The only specimen in the Challenger collection is an im- 

 mature female 7 mm. in length and 5 mm. in breadth ; the two specimens described by 

 Chilton are both males, 8 mm. in length and 5 mm. in breadth. The head is broad and 

 terminates in a comparatively long rostrum. The body, excluding the terminal segment, 

 is circular in outline, and the terminal segment projects back for some considerable 

 distance and is proportionately longer than in any other species. The first three free 

 thoracic somites are separated from their respective coxal plates by sutures; the coxal 

 plates are all short and truncate at their distal extremities. Beddard states (18846, p. 73) 

 that "the tergum of the sixth segment is entirely absent " ; this, however, is not the case, 

 but the tergum of both the sixth and seventh somites is very narrow, and the hindmost 

 sutures of both are obsolete for some distance on either side of the middle Hne, so that 

 the middle portions of these somites and that of the first abdominal segment are fused 

 together. A similar condition is seen in S. australiensis, Beddard, S. elongata, Beddard, 

 S. bouvieri, Richardson, and S. aspera, n.sp. 



The pleural plates of the second and third abdominal segments are also truncate and 

 do not extend beyond the anterior margin of the terminal segment ; the latter is roughly 

 pentagonal in outline, terminates posteriorly in a truncated extremity which is slightly 

 concave, and bears a median and two lateral carinae on its dorsal surface. 



Occurrence. Off St Francis Island, South Australia, 6-13 fathoms. 



36. Serolis tuberculata, Grube. 



S.tuberculata, Grube, 1875, p. 227; Beddard, 18846, p. 67, pi. vi, figs, i, 2; Whitelegge, 190 1, p. 236; 

 Chilton, 1917, pp. 392, 394, text-figs. 1-9. 



Diagnostic characters. The largest recorded specimen of this species is a female 

 measuring 19 mm. in length and 17 mm. in breadth; the measurements given for the 

 male are 12 mm. in length and about the same in breadth, so that, as is usually the case, 

 the male is proportionately broader than the female. 



As Chilton (1917, p. 394) points out this species is readily distinguished from other 

 Australian species by " the series of pointed tubercles along the posterior margins of the 

 anterior segments of the peraeon, and by the median tubercles on all the segments ". 

 The tubercles are most numerous on the fifth segment, where there may be as many as 

 nine on either side of the median one. The tergal portion of the sixth thoracic somite is 

 very narrow, whilst the middle portion of the seventh somite has disappeared; the 

 first three free thoracic somites are separated from their respective coxal plates by 



