110 THE FRESH- WATER CRAYFISH— THE CAPE CRAWFISH 



F. The Vascular 'System {contirmed). 



Trace the sternal artery through the aperture in the nerve cord ; and note 

 that it divides ventrally into the ventral thoracic artery and the inferior 



Cerebral ganglia- 

 Stomach 



Visceral nerve 



Adductor itiuscle 

 of Mandible 



\. Ophthalmic 

 artery^ 

 Hepatic 

 artery 

 Antennary 

 artery 

 Heart 

 ■ Testis 



Sternal artery 

 '£xtensor muscles 

 Vas deferens 



Intestine 

 Endophragmal skeleton^ 



Superior abdominal 

 artery 



Flexor muscles 



, - \-CircumGesophageal 

 commissure 



Postoesophageal 

 commissure 



Suboesophageal 

 ganglion 



1st Thoracic 

 ganglion 



• -Loop for 

 Sternal artery 



5th Thoracic 

 ganglion 



Sternal canal 



1st Abdominal 

 ganglion 



- 6th Abdominal 

 ganglion 



Pig. 33.— The Cape Crawfish {/asus). A. Dissection of a mcde showing the general structure ; 



B. the nervous system. 



abdominal artery — vessels which run in close connection with the nerve cord 

 and which supply the limbs and other organs of the body. 



Examination of a Larval Form (Phyllosoma). 



Examine under the microscope, or with a lens, a larval form (Phyllosoma) of 

 the Crawfish. Note and draw : — 



(a) The large head region, distinct from the thoracic region, and the very 

 small abdominal region. 



