NO. 2194. NORTH AMERICAN PARASITIC COPEPODS— WILSON. 



43 



Each egg (laughter-cell as it passes into the oviduct accumulates yolk 

 and food material and becomes a mature egg. In the oviduct these 

 eggs are strongly flattened antero-posteriorly and packed together 

 like a row of coins. The cement glands are entirely separate from 

 the oviducts and open into the latter close to the vulvae, covering 

 each egg with an external membrane just before it passes out into the 

 ecg strings. Here the eggs are again packed like a row of coins, but 

 separated by the . ^-^ 



are now 



membranes. The nauplius 



and metanauplius stages 



have not been seen, but in 



all probability are passed as 



free-swimming larvae in the 



plankton. 



In the genns Sarcotretes 

 the first copepodid larvae 

 sought as a temporar}'^ host 

 the same fish to which the 

 fertilized female afterwards 

 fastened as a permanent 

 host. But these copepodid 

 larvae fasten not to the gills 

 but to the fins of the fish by 

 means of their strong che- 

 late second antennae. At 

 the close of this stage the 

 larva fastens itself to the 

 fish by firmly cementing to 

 the fish's skin the terminal 

 disk of a stout frontal fila- 

 ment developed in the an- 

 terior part of the ccphalo- 

 thorax, and remains thus 

 attached during the subse- 

 quent copepodid stages. These stages are called pupal, because 

 during them the antennae, mouth parts, and swimming legs all lose 

 their distinct segmentation and often their setae and become swollen 

 and clums}'. The reproductive organs, however, are developed so that 

 at the close of the last pupal stage, when the appendages are re- 

 stored to their former condition, the young males and females shed 

 their frontal filaments and swim about again freely in the plankton 

 where fertilization occurs. After fertilization the males die and 

 the females seek again the same species of fish for their final host, 

 fastening to its skin by the chelate second antennae. They then bur- 



FlO. B. TlTE MAI.E (left) AND KEMAIE (RTfiHT) 



COIEl'ODID I.AltVAE OF" SaUCOTUETES SCOIELI. 

 AktEU Ju.NGEUSEX: actual LEXGTU of FEMALE, 



2mm. 



