25 



PLATE XIII. 



LOBSTER AND CRAYFISH continued. 



GENERAL ARRANGEMENT OF INTERNAL ORGANS 



FIGS. 1, 2, 3. BODY IN SECTIONAL PLAN AND ELEVATION 



Mouth. 

 Gullet. 



ALIMENTARY SYSTEM 



Stomach, with its cardiac or anterior end (Gr. Mrdia, the heart), and its 



pyloric or posterior end (Gr. puloros, a gatekeeper) leading into 

 Intestine ending in 

 Anus. 

 Liver made up of two symmetrical halves. 



CIRCULATORY SYSTEM j , 



( Arteries Sternal, superior abdominal, and inferior abdominal. 



RESPIRATORY SYSTEM Branchiae (Gr. gills), twenty on each side in Lobster, eighteen in Crayfish. 

 HENAL SYSTEM Green glands situated at the base of antennae. 



( Supra-cesophageal ganglia. 

 NERVOUS SYSTEM . \ Circum-cesophageal commissures. 



i buD-ffisopnageal ganglia. 



V Chain of eleven ganglia. 



' Testes with their vasa deferentia opening on the base of last thoracic 



REPRODUCTIVE SYSTEM I appendages (fig. 2). 



Ovaries with their oviducts opening on the base of last thoracic appen- 

 dages but two (fig. 3). 



