CLASSIFICATION 



271 



somites, it seems strange that he should have omitted this very definite type of modifica- 

 tion, more especially since he had in his possession material representing three of the 

 species concerned, namely S. bouvieri, S. australieusis and S. longicaiidata. 



It is obvious from the above, that Nordenstam's classification, as it stands, cannot be 

 accepted. If the sub-division of the genus Serolis along the lines indicated above is to 

 be established, then it is essential that a fifth subgenus should be formed to contain 

 S. bouvieri, S. elongata, S. australieusis, S. longicaiidata and the two new species 

 S. platygaster and S. aspera. I maintain, however, that the genus is best left intact, and 

 for this reason I do not suggest a name for this extra subdivision. 



GENERAL MORPHOLOGY 



The following notes, dealing with certain features in the anatomy of the Serolids, are 

 included in the introductory part of this paper as they apply to the group as a whole and 

 have not been described in detail in earlier papers. They include the structure of the 

 maxillula, the maxilla and maxilliped, the interpretation of parts being based on the 

 views expressed by Hansen (1925), as well as certain points of more general interest. 



According to Hansen (1925) the maxillula in the Isopods consists only of a sympod 

 made up of three segments : the endopod and exopod are wanting. 



-I o. i^v 



Fig. I . The maxillula and maxilla of species of Serolis. 



a, maxillula of S. cornuta, Studer: x 30. b, maxillula of S. orhiculata, n.sp. : x 140. c, maxilla of S. cornuta, 

 Studer: : 30. d, maxilla of 5. nototropis, n.sp.: x 104. e, maxilla of S. orbicidata, n.sp.: x 140. 



