41 



The nerve supplying the antennules has a similar branch- 

 ing at its termination to that of Lepeophtheirus. 



In the adult Lerniea no trace of a nervous system could 

 be made out, and certainly if present at all it is very much 

 reduced. 



The Reproductive Organs. 



The reproductive organs of Lemma, like those of 

 Lepeophtheirus, are bilaterally symmetrical. In the 

 Cyclops stage of the female (Plate V., fig. 1) the ovaries 

 (o.) are pjaiform organs lying on each side of the 

 stomach. They are situated on the ventral surface near 

 the posterior end of the cephalo-thorax. Each oviduct 

 [od.) arises near the posterior end, and courses posteriorly 

 as a narrow tube. When it enters the genital segment it 

 expands rapidly, ending in a large sac, the receptaculum 

 seminis (s), communicating with the vulva {vu.). The 

 oviduct has no distinct loops, and no cement gland is 

 found. 



In the adult male (Plate IV., fig. 5) the testes {t.) occupy 

 the same positions as the ovaries in the female. The vasa 

 deferentia are straight, narrow tubes coursing posteriorly 

 and terminating in the sacs of the spermatophores. A 

 cement gland is present, as in Lej^eophtheirus. 



The ovary in the course of the metamorphosis under- 

 goes great change of position. It is removed from the 

 cephalo-thorax into the genital segment. It occupies a 

 narrow region at the apex of the deep indentation (Plate 

 v., figs. 4 and 5, o.). The two ovaries have also practically 

 fused together, no separation is visible in transverse sec- 

 tion. The united ovaries are produced into horn-like pro- 

 jections anteriorly and posteriorly (Plate Y., fig. 5). The 

 oviducts (od.) arise near the apex of the anterior horns, 

 pass across the segment to its ventral surface, and then 



