76 LABORATORY DIRECTIONS 



2. From the lower side of the ovary trace the large oviduct 

 downward to the external openings on the basal segment of the 

 third pair of walking legs. 



3. On the external surface upon the median line between 

 the fourth and fifth pairs of walking legs observe the annulns 

 ventralis. Following copulation sperm is stored in this until the 

 time of egg laying. 



THE MALE 



1. The testes lie immediately below the pericardial sinus. 

 They consist of two anterior lobes and one median posterior 

 lobe. 



2. The vas deferens is a long coiled tube extending along 

 the side of the body, from the lower part of each testis to the 

 genital opening, in the basal joint of the fifth walking leg. Before 

 the breeding season has passed the vas deferens will be filled 

 with a white mass of sperm. 



3. Reexamine the appendages of the first and second ab- 

 dominal segments, as it is by their aid that a tube is formed 

 which conducts the sperm from the genital openings of the male 

 to the annulus ventralis of the female. Make a drawing of the 

 reproductive organs of your specimen. 



See demonstration specimen of female crawfish carrying 

 eggs on the swimmerts. The eggs, after fertilization, become 

 attached to the swimmerts were they undergo development. 



DIGESTIVE SYSTEM 



1. The digestive tube extends from the mouth to the anus. 

 The liver (or more correctly the hepato-pancreas) is a large 

 bilobed organ which lies below the ovaries or testes. These lobes 

 lie along either side of the digestive tube. Each lobe connects 

 by a duct with the main digestive tube. 



2. Turn the animal over and on the ventral side examine 

 the mouth between the jaws. Insert a probe into the mouth. 



