CALLINECTES HASTATUS. 147 



(b) Male 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. (a) The liver fills all of the body-cavity not 

 occupied by other organs. Remove the portion of it that is in the 

 region of, and anterior to, the stomach, noting its connection 

 with the alimentary tract. 



(6) 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 

 caecum. 



(c) Follow the delicate intestine back beneath the heart. 

 Between the posterior edges of the flank is a white mass composed 

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

 abdominal segments, follow this caecum to its connection with 

 the intestine, and follow the latter to the anus, noting its chiti- 

 nous lining. 



(d) Cut out the alimentary tract, open the stomach, and 

 examine the grinding and straining apparatus. 



Make a drawing of the alimentary canal. 



Excretory Organs. Examine the antennary gland (green 

 gland) on the inside of the carapace opposite the base of the 

 antenna. It consists of a thin bladder, and, anterior to this, a 

 mass composed of a coiled tube which opens at the base of the 

 antenna. 



Nervous System. Find the ring of ganglia around the 

 ventral end of the sternal artery. 1 Trace the nerves from this 

 to the appendages and to the small abdomen. Trace the circum- 



*In a fresh specimen the ganglia can be more easily studied after 

 treating them with strong alcohol for a moment. 



