202 CEYLON PEARL OYSTER REPORT. 



Of the appendages, the second antennae are especially large and stout ; their 

 terminal claw is bent abruptly at a right angle one- third its length from the tip, and 

 is armed on the inner margin of the basal third with a long curved and sharp spine, 

 a short and blunt one, and a long slender hair (fig. 36). The second maxillae are 

 similar to those of the female but larger and more powerful. The outer branch at 

 the tip is nearly twice as long as the inner, while the three spines which make up the 

 rudimentary exopod are much larger and stouter. The maxillipeds and legs are the 

 same as in the female. The ventral surface of the genital segment is also covered 

 with spines, larger and rather more numerous than in the female (fig. 47). 



Total length 3 millims., length of carapace 0*8 millim., width of same 1*9 millims., 

 length of free segments 1'08 millims., of genital segment 0'8 millim. 



This new genus is very interesting since it stands as a connecting link between the 

 Euryphorinae and the Pandarinae. At first sight it would be taken for a Nogagus 

 species, showing that which was so long sought after, a mature female with her egg- 

 strings. But the description just given excludes it from that genus. The dorsal 

 aspect, to be sure, is very similar to that of a typical Nogagus ; the carapace is 

 perhaps a little too short, but the free segments, the genital segment, and the 

 abdomen are almost identical with those in some species of Nogagus. When we 

 examine the ventral surface and the appendages, however, we find radical 

 differences. 



First there are no traces of sucking disks which are found in all the species of 

 Nogagus. The mouth-tube, mandibles and second maxillae are like those found in 

 the Euryphorinae and quite different from the typical form of the Pandarinae. 



The mouth- tube is short and broadly rounded at the tip instead of being narrow 

 and pointed. The mandibles are curved at the tip, toothed on the concave border, 

 and come together end to end, instead of being straight, with the toothed margins 

 interlocked for their entire length. The second maxillae are very long, pointed, and 

 bifurcate at the tip, with a well defined exopod, instead of being short, triangular or 

 broadly laminate, and without any trace of a second ramus. 



The second maxillipeds have a simple swollen basal joint and an ordinary terminal 

 claw unlike the distorted form in 'Nogagus with its swellings and knobs. 



The swimming legs have three-jointed rami, except those of the first pair ; a 

 typical Nogagus has no ramus with more than two joints. We have here then a 

 genus whose body-form is almost exactly like that of Nogagus, while its appendages 

 are all modified and approach much nearer to those found on Euryphot^us, Alebion, 

 and Dysgamus. And since in any sy sterna tization, but more especially here among 

 the Parasitic Copepods, the appendages are of more value than the body form in 

 determining relationship, this genus must be placed with the Euryphorinae. 



It will be the only genus in the sub- family possessing three free thorax segments, 

 but as it is an intermediate form, any close conformity to the characteristics of a single 

 family could not l>e reasonably expected. 





