South African Crustacea. 47 



4 anterior dorsal teeth behind the foremost dorsal tooth. The 

 antennal tooth and the antero-lateral tooth of the carapace are 

 acute and conspicuous, but this seems to be a character 

 common to the South African specimens. The telson agrees 

 in length with the rostrum . Another specimen from the same 

 station, measuring 81 mm., has a carapace 28 mm. long, with 

 rostrum 10 mm., dorsal teeth 28, and no ventral teeth. 



In the mouth organs of different specimens there do not 

 appear to be variations on which any reliance can be placed 

 for specific discrimination. 



The Epicaridean parasite here figured, with a specific 

 name alluding to the genus of its host, was lodged among 

 the anterior pleopods of a large specimen taken at Station 

 A 1229. The parasite itself has the characters of a genus 

 very clearly described by Professor Sars in his Crustacea 



Hemiarthrus ncmatocarcini, n. sp. 



of Norway (vol. 2) under the preoccupied name Phryxus. 

 For this Giard and Bonnier substituted the name Hemiar- 

 thrus, rather unfortunately as the closely similar name 

 Hemiarthrum had already been used. The male of the 

 new species is distinguished from that of H. abdominalis 

 (Kroyer) by the very different shape of its oval pleon. On 

 its first extraction from an apparently symmetrical situation 

 the female may well excite surprise by its extremely lop- 

 sided structure, but Sars has explained that " the parasite 

 is always found to be firmly attached by the aid of the one 

 series of legs to the basal part of one of the anterior pleopods 

 of its host, sometimes the right, sometimes the left, and the 

 distortion of the body to the one or the other side depends on 

 this mode of attachment " (Crustacea of Norway, vol. 2, p. 217). 

 Nevertheless, the distortion, which is so adequately explained 



