162 ARTHROPOD A. 



into the pericardial cavity. Can you determine how many 

 sinuses there are? Do you understand how the heart receives 

 blood? 



Reproductive System. Beginning antero-laterally, on one 

 side, dissect out the reproductive organs, noting at the same time 

 the distribution of arteries. 



(a) Female reproductive organs. 1 Each ovary passes inward 

 and backward, anastomoses with the one of the other side 

 behind the stomach, and extends back to the abdomen. On a 

 level with the posterior part of the stomach a branch passes down- 

 ward and outward and is continuous with a dense, white organ, 

 the seminal receptacle. Leave this receptacle in place, but re- 

 move the entire ovary. 



(6) Mate reproductive organs. The usually slender testis 

 which is large during the season of activity passes inward and 

 backward, anastomoses with its fellow of the other side behind 

 the stomach, and is continued as a thick, much-coiled tube, the 

 vas deferens, to the median side of the flank. It then runs for- 

 ward nearly to the stomach, turns back again, and enters the 

 substance of the flank. By removing the top of the flank and 

 the upper side of the coxopod of the swimming leg, it can be fol- 

 lowed to its external opening. 



Digestive System. 1. The liver is large and fills a large 

 part of the body cavity. Remove the portion of it that is in 

 the region of, and anterior to, the stomach, noting its connec- 

 tion with the alimentary tract. 



2. The stomach is a chitinous box divided into a larger car- 

 diac and a smaller pyloric portion. On each side find the duct 

 from the liver, and a slender, white, coiled tube, the pyloric 

 c&cum. 



3. Follow the delicate intestine back beneath the heart. 

 Between the posterior edges of the flank is a white mass com- 

 posed of a coiled tube, the intestinal ccecum. Remove the 

 terga of the abdominal segments, follow this ca3cum to its con- 

 nection with the intestine, and follow the latter to the anus, 

 noting its chitinous lining. 



1 The specimen must be large and mature. 



