1910;] FRESHWATER CRUSTACEA FROM THE TKAXSVAAL. 161 



is put forward with all the more hesitation, seeing, first, that 

 it may be merely superficial, and secondly, that the generally 

 accepted view is, that proliferation takes place from the proximal 

 segment, which is in this case together with the second segment 

 admittedly short in comparison with that of the antennule of 

 other Centropagidae. Ten aesthetes were found on the female 

 antennule (they are coloured blue in the figure). The spines from 

 segment fifteen onwards are finely serrated. On segments three 

 to nine marginal groups of small setae are borne on the side other 

 than that bearing spines and aesthetes : on the same side, and 

 situated at the distal extremity of each segment from eight to 

 thirteen, is a group of minute setae. The male geniculated 

 antennule consists of the normal twenty-three joints. 



The antenna is very much like that of Diaptomus castor as 

 figured by Schmeil (9) : the exopodite consists of eight joints 

 instead of seven ; all the joints except the third and eighth bear 

 one bristle each ; the third joint has two bristles and the eighth 

 is provided with three long distal hairs and a much shorter 

 proximal : the terminal joint of the endopodite has two lobes, one 

 bearing nine prominent setae, the other seven and a few 

 inconspicuous hairs marginally at the base of the long seta lying 

 opposite the exopodite. A row of eight small hairs is placed 

 distally near the external marginal edge of the second joint of the 

 endopodite : the basipodite is provided internally with one stout 

 bristle. 



The mandible : the gnathobase is stout and broad at the base, 

 but half - way between the basal tubercles and the point of 

 insertion of the palp, there is a marked " neck." The basipodite 

 of the palp bears four bristles, two setae, one serrated and one 

 smooth : the endopodite is two-jointed : a lobe is present on the 

 proximal joint which bears four smooth bristles ; the distal segment 

 carries seven long smooth hairs : in addition, on the outer margin 

 of this distal segment are developed small setae which extend 

 partly along the base of the terminal hairs. The exopodite 

 appears to be four-jointed ; the distal segment is to all appearances 

 single, and bears three long hairs ; the other segments each carry 

 one long hair springing from the internal margin. 



The maxillula (fig. 50) and maxilla (fig. 51) have nothing 

 remarkable apart from what these appendages in Diaptomtibs 

 possess. In the maxillula, the first endite of the first basal joint 

 bears ten stout and three finer bristles ; the second endite has 

 four bristles ; the third endite has three ; the first exite is 

 provided with nine large bristles and the second exite with one ; the 

 second basal joint and its endite together carry fourteen triples. 

 The maxilla is very like that of Diaptomus castor, but the 

 third and fourth exites have two bristles each instead of three, 

 and the fifth exite has four bristles instead of three. 



The first thoracic appendage or inaxilliped is in the main like 

 that of D. castor but is quite different from that of Adiaptomus. 

 Thesecond segment calls for special description. D:s ally, on the 

 Proc. Zool. Soc— 1910, No. XL 11 



