82 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 53. 



no maxillipeds ; all the swimming legs close together and near the 

 head. 



Suh family characters of Copepodid male (genus Lernaeocera) . — 

 Body like that of Cyclops^ composed of a cephalothorax covered 

 with a carapace; three free thorax segments, a fused fifth and genital 

 segment, and a short, one-jointed abdomen ; anal laminae small, each 

 armed with 4 or 5 minute setae. Antennae and mouth parts as 

 in the female, with the addition of a pair of well-developed uncinate 



maxillipeds; two pairs 

 of biramose swimming 

 legs, with two- jointed 

 rami, third and fourth 

 pairs uniramose, rami 

 also two-jointed. 



Ontogeny of genus 

 Lernaeocera. — The gen- 

 ital protoplasm in the 

 posterior end of the 

 ovary forms Qgg 

 mother cells and egg 

 daughter cells, the lat- 

 ter filling the anterior 

 end of the ovary with- 

 out definite arrange- 

 ment. These oocytes 

 acquire food and yolk 

 material as t\\^j pass 

 into the oviduct, and 

 are there strongly flat- 

 tened and packed 

 tightly in a single row. 

 The cement glands are 

 entirely separate from 

 the oviduct and open 

 into the latter just in- 

 side the vulvae. Each 

 egg is surrounded by an external membrane of cement material 

 as it passes out through the vulva into the external sack, where it 

 is again flattened and arranged with the others like a row of coins. 

 The larva hatches as a typical nauplius with the usual three pairs 

 of appendages, and one pair of posterior balancers. The nauplius 

 is transformed into a metanauplius while swimming about freely in 

 the plankton. At the -first copepodid stage it seeks out as a tem- 

 porary host some fish other than the one which is afterwards to serve 



Fig. C— The male (left) and female (right) copepodid 



LARVAE OF LERNAEOCEKA BRANCHIALIS, AFTER A. SCOTT: 



Actual length of female, 2.30 mm. 



