83 



ZOO LOOT. 



for the ingress of the venous blood. The colorless blood 

 is pnmj">ed by the heart backwards and forwards through 

 three anterior arteries, one median and two lateral, the 

 median artery passing towards the head over the large 

 stomach, and the two lateral, or hepatic arteries, passing 

 to the liver and stomach. From the posterior angle of the 

 lieart arise two arteries; the upper, a large median artery 

 (the superior abdominal), passes along the back to the erd 

 of the abdomen, sending off at intervals pairs of smi^U 

 arteries to the large masses of muscles filling the abdomi- 

 nal cavity; the lower is the second or sternal artery, which 

 connects witli one extending along the floor of the body 

 near the thoracic ganglia of the nervous cord. There are 

 no veins sucli as are present in the Vertebrates, but a series 

 of venous channels or sinuses, tlirough which the blood re- 

 turns to the heart. There is, however, a large vein in the 

 middle of tlie ventral side of the body. 



The blood is driven by the heart through the arteries, and 



flah 



Fig. 97. — C, first maxilUpede of lobster. 



a large part of it, forced into the capillai'ies, is colleefed bv 

 the ventral venonw sinus, and tlienco passing tlirougli the 

 gills (Fig. 97, gill), where it is oxygenated, returuijig to 

 the heart. 



The gills arc appendages of tlie three pairs of maxilli- 

 podes and the five ptiirs of feet, and are contained in a 

 cliam))er foniied liy the carapace; tlie sea-water jiassing into 

 the cavity between the body and the free edge of the cara. 



