PLATE XXI!. 



Class CRTJ STAGE A continued. 

 THE LOBSTER continued. 



FIG. 1. LONGITUDINAL SECTION, SOMEWHAT TO THE LEFT OF THE MIDDLE LINE. 

 x|. 



* 



ce. oesophagus : m. muscles of the stomach : li. heart : o. a. ophthalmic 

 artery : s. a. superior abdominal artery : s. sternal artery : i. a. 

 inferior abdominal artery : n. nerve cord : i. intestine : g. 

 genital opening (male). 



PIG. 2. PLAN OF THE CIRCULATORY SYSTEM. 



Ji. heart : s. a. superior abdominal artery : st. sternal artery : i. a. 

 inferior abdominal artery: s. venous sinus sending afferent 

 vessels to the gills. (The efferent vessels from the gills to 

 the pericardial sinus are represented by the six dark lines.) 



FIGS. 3, 4, 5. DORSAL, VENTRAL, AND SIDE VIEWS OF THE HEART, x 1. 



o. a. ophthalmic artery : a. antennary artery : h. hepatic artery : s. a. 

 superior abdominal artery : st. sternal artery : o. openings into 

 the heart. 



FIG. 6. VENTRAL VIEW OF THE BLOOD SINUS AT THE BASE OF THE GILLS, x |. 

 s. sinus receiving vessels from the appendages. 



