On a new Species of the Tsopod Genus Serolis. 299 



XXXVI. — A new Species of the Isopod Genus Serolis. 

 By W. T. Calman, D.Sc. 



(Published by permission of the Trustees of the British Museum.) 



Among the numerous species of the genus Serolis, S. latifrons, 

 Miers, stands apart on account of the structure of the uropods, 

 which, as Beddard* pointed out, " recalls that characteristic 

 of the Sphasromidae." Beddard also stated that the species 

 differed from all the other members o£ the genus in having 

 minute "epimera" separated by suture from the first abdo- 

 minal somite. It will be shown below, however, that these 

 structures really belong to the last thoracic somite, of which 

 no trace persists on the dorsal surface in any other species. 



The Museum has recently received from the South Shetland 

 Islands specimens of a new species agreeing in these and 

 other characters with S. latifrons. The two species might 

 very well be treated as forming a distinct genus, but it is not 

 convenient to do so without undertaking the re-grouping of 

 the remaining species of the genus Serolis. As a contribution 

 towards this re-grouping, the following arrangement, based on 

 some of the more obvious characters, is suo*o;ested : — 



A. Uropods without endopod, exopod articu- 



lated to outer margin of the prolonged 

 spiniform peduncle. Tergum of last tho- 

 racic somite interrupted in the middle, 

 where the first abdominal comes in contact 

 with the penultimate thoracic tergum ; 

 lateral portions persisting as a pair of 

 minute sclerites each with a coxal plate 

 separated by suture Group of S. latifrons. 



B. Uropods with endopod and exopod movably 



articulated with the peduncle. Tergum 

 and coxal plates of last thoracic somite 

 absent. 



a. Tergum of penultimate thoracic somite. 



complete Group of S. paradoxa. 



b. Tergum of penultimate thoracic somite 



interrupted in the middle, so that the 

 first abdominal comes in contact with 

 the antepenultimate thoracic tergum . . Group of S. tuberculcda. 



The first of these groups will contain, in addition to 

 S. latifrons, only the new species described below. The 

 group of S. tuberculata comprises the six Australian species 



* Rep. Isopoda ' Challenger,' pt. 1, 1884, p. 46. 



