86 ZOOLOGY DIEECTIONS 



3. The para-esophageaJ connectives are a pair of nerve 

 cords which connect the brain, around the esophagus with the 

 hinder part of the nervous system. Behind the esophagus they 

 are connected by a transverse commissure. 



4. The post-esophageal mass lies behind the mouth. It 

 supplies the mandibles, maxillae, and first and second maxilli- 

 peds with nerves. 



5. The thoracic nerve chain consists of six ganglionic 

 masses, which supply nerves to the third maxillipeds and the 

 five pairs of walking legs. The first one lies very close behind 

 the post-esophageal mass. 



6. Trace the ahdoviinal nerve chain with its six ganglionic 

 masses. 



7. Make a drawing to show the nervous system and label 

 all parts. 



8. A statocyst occurs on the dorsal surface of the basal 

 joint of each antennule. Remove the rostrum and locate opening 

 of statocyst by means of a blunt probe. 



Excretory System 



1. The kidneys or green glands lie in the ventral part of 

 the head anterior to the mouth. Each kidney connects with the 

 exterior on the posterior surface of the tubercle located upon 

 the basal segment of the antenna. 



REFERENCES 



Andrews, E. A., 1906. The Keeping and Rearing of Crawfish 

 for Class Use. Nature-Study Review: Vol. 2, pp. 296- 

 301. 



Herrick, F. H., 1911. Natural History of the American Lobster. 

 Bull. U. S. Bureau Fisheries 29. 



