322 Animal Biology 



Carapace 

 removed 



Sternal 



artery 

 hascle — 



Ventral thoracic 

 artery 



Ventral sinus 



Pericardial s/nus 



Heart 



Ostium 



hasc/e 



Gonad 



Intestine 

 Oigest/i^e jland 

 Efferent /esse/ 



Gill 



Neri/e cord 

 Carapace 



Fig. 130. — Diagram of cross section through the posterior thoracic region of a 

 crayfish. Arrows show direction of blood flow. (From Potter: Textbook of 

 Zoology, The C. V. Mosby Co.) 



4 



Fig. 131. — Fresh-water shrimp (Palaemonetes sp.) of the class Crustacea, 

 phylum Arthropoda. (From a photograph by P. S. Tice. Copyright by General 

 Biological Supply House, Inc., Chicago.) 



