DESCRIPTION OF SPECIES 357 



The head is broadest at the level of the eyes and ends anteriorly in a very long rostrum ; 

 a median spine is present on its posterior border and also on those of the thoracic somites. 

 The central portions of the terga of the sixth and seventh thoracic somites are fused 

 with the tergum of the first abdominal segment, that is, the hindmost sutures of the 

 sixth and seventh somites are obsolete in the middle line. The coxal plates are closely 

 applied together; according to Beddard those of the free somites are all separated by 

 sutures, but I have failed to find more than three pairs of sutures present on the third, 

 fourth and fifth somites respectively. 



In the male the coxal plates of the seventh thoracic somite extend for a short distance 

 beyond the extremities of the pleural plates of both second and third abdominal seg- 

 ments, but not as far as the points of attachment of the uropoda ; in the female they do 

 not extend beyond the level reached by the pleural plates of the second abdominal 

 segment. 



The terminal segment is more or less triangular in shape, with a median keel and a 

 truncate, slightly emarginate extremity. Its dorsal surface is covered with tubercles 

 which are arranged irregularly except for a transverse row which extends across the 

 segment slightly posterior to the articulation of the uropoda : one of these tubercles, 

 close to the lateral margin on either side, is considerably larger than the rest. The 

 exopod of the uropod is shorter than the endopod and its distal end is truncate ; the 

 endopod is rounded distally and reaches to the end of the terminal segment. 



Occurrence. South Australian coast, 38 fathoms. 



34. Serolis elongata, Beddard. 



S.elongata, Beddard, 1884a, p. 335; 18846, p. 71; Whitelegge, 1901, p. 236; Chilton, 1917, p. 393. 



The original description of this species, which is based on an examination of a single 

 adult female, is extremely brief, and no account of the form of the mouth parts and 

 other appendages is given. More recently the species has been collected on two occa- 

 sions: it was recorded by Whitelegge in 1901 in his report on the Isopoda of the Thetis 

 Expedition and in 1917 by Chilton, who examined a specimen in the collections made 

 by the F.I.S. 'Endeavour'. Neither of these authors have added anything further to 

 Beddard 's description. 



Diagnostic characters. The adult female measures 10 mm. in length and 6-5 mm. 

 in greatest breadth. The surface of the body is almost smooth, except that each thoracic 

 somite is furnished with a median dorsal spine on either side of which a row of short 

 tubercles extends along its hinder border and is prolonged on to the coxal plate. The 

 hindmost sutures of the sixth and seventh thoracic somites are obsolete for a short 

 distance on either side of the middle line : I have examined the British Museum specimen 

 and find that the first three free somites are separated from their respective coxal plates 

 by sutures, and also that the coxal plates of the seventh somite extend beyond the pleural 

 plates of the second abdominal but not as far as those of the third. The pleural plates 

 of these segments are short and hardly extend beyond the anterior margin of the 

 terminal segment. The margins of the terminal segment are serrated. A median 



D VII ^4 



