44 PHYLUM ARTHROPODA 



branched organs. The oviducts are paired and lead to the exter- 

 nal sexual openings in the first abdominal segment. Appended to 

 the first abdominal segment may be a pair of egg sacs containing 

 fertilized eggs which are cemented together by means of a secre- 

 tion of the oviduct. In the male the reproductive gland is the 

 median testis, which communicates by means of paired sperm 

 ducts with the external sexual openings, which are also in the 

 first abdominal segment. The spermatozoa collect in the terminal 

 portion of each sperm duct and form there a small mass known 

 as a spermatophore. The two spermatophores, during the act of 

 pairing, pass to the female and fertilize the ova. The male animals 

 are much less numerous than the females. 



The reproductive glands of the copepod can be observed as 

 above described only during times of sexual activity. At other 

 times they can be seen only in part or not at all. 



The muscular system can be easily seen to consist of striated 

 muscle fibers. Longitudinal as well as converging fibers will be 

 seen at each appendage. 



The nervous system may be seen in favorable specimens as a 

 ventral strand in the cephalothorax connecting with the large 

 dorsal brain. 



Exercise 4. Draw a side view of the animal, showing as many of the 

 internal organs as you have observed. 



