Chap. XII.] 



THE CRAYFISH. 



241 



Behind the levator muscle of the stomach are seen the anterior 

 lobes of the spermary or testis (a. t.\ the median posterior lobe 

 being seen further back akp. t. Between these is the heart (A.), 

 with two dorsal openings or valves (d. v.). The heart is held 

 in position by fibrous bands, the alae, fixed to its corners. 



st. 



r.ql. 



.t. 



int. 



FIG. 75. CRAYFISH GENERAL ANATOMY. 



a. d. g. Anterior part of digestive gland. . g. Anterior gastric muscle. 

 a. t. Anterior lobe of testis. c. os. Cardiac ossicle. c. p. Cardiopyloric 

 muscle, d. v. Dorsal valve of heart, gr. gl. Green gland, h. Heart, int. 

 Intestine. 1. m. Levator muscle, m. m. Mandibular muscle, p. g. Posterior 

 gastric muscle, p. d. g. Posterior part of digestive gland, p. os. Pyloric 

 ossicle, p. t. Posterior lobe of testis. s. Saccular part of green gland, s. a. a. 

 Superior abdominal artery, st. Stomach, v. d. Vas deferens. 



Anteriorly it gives off a median ophthalmic artery and two 

 antennary arteries, the cut ends of which are figured in the 

 16 



