Contributions to the Crustacean Fauna of South Africa. 375 



It must be noted that this definition is based on the female only ; 

 for the sexual differences one must turn to C. darwinii. Here the male 

 seems to differ from the female in the greater development of the boss 

 on the telsou, the swelling- of the lateral portions of the 5th peraeon 

 segment, and the development of a tooth on the base of the hand of 

 the 1st peraeopod (gnathopod). 



Here a difficulty arises in regard to the present species. The sexual 

 differences are very much more pronounced than in C. darwinii. In 

 fact, the rudimentary character of the inner ramus of the uropods 

 might even be thought to necessitate the erection of a new genus. 

 And this may indeed become necessary in the future, but for the 

 present I prefer to place the new species in the genus Cassidias 

 because the male of the type-species remains unknown. Very probably 

 when it is discovered it will be found to resemble that of darwinii more 

 or less closely, and a new genus can then be made for the species 

 described below. 



In 1910 Thielemann described a third species C. trituberculata 

 from Japan. This also is known only from the female, and in the 

 character of the telsouic apex differs rather conspicuously from the 

 type-species. In other respects it seems to be a true Cassidias, the 

 unmodified mouth-parts possibly being due, as Thielemann remarks, 

 to immaturity. Nevertheless, when the male is discovered, it would 

 not be surprising if it had to be removed to another genus. 



Both C. aryentinea and darwinii inhabit the southern portions of 

 Southern America and the neighbouring islands. 



CASSIDIAS AFRICANA n. sp. 

 (Plate XVI. Figs. 15-17.) 



Body strongly convex, nearly parallel-sided, anteriorly (at least) 

 almost smooth, glabrous. Head with anterior margin slightly angular, 

 with a short blunt median process. Head and 1st peraeon segment 

 minutely shagreened. Peraeon segments with the posterior margins 

 becoming increasingly more grauulose posteriorly, the granules on 

 segments 5 and 6 being more or less distinctly segregated into 2 

 transverse rows. Each side-plate with a little tuft of soft setae. 



Pleou segment 4 entire, its posterior margin granulose, the lateral 

 sutures also marked with granules, one tuft of setae on the lateral 

 portion of segment 4 and another submedianly. 



Telson broader than long, surface granulose, the central portion in 

 ^ produced into a long, though stout, median process, apically sub- 

 acute, reaching back considerably beyond the telsouic apex ; in $ 

 a similar though very much smaller process, not nearly reaching the 



