128 MOLLUSC A. 



The pulmonary artery passes along this band, sends a 

 branch into each footstalk, which, penetrating the substance 

 of the gills, conveys the blood to its different divisions. 



The systemic veins depart from the gills at the opposite 

 extremity. These unite at the inferior band, and from each 

 gill a vessel proceeds to the single central or systemic heart 

 or ventricle. In some of the animals of this class the sys- 

 temic veins are somewhat enlarged, and assume the appear- 

 ance of auricles. The two pulmonary, or rather the sys- 

 temic veins, enter the heart at the opposite side, each at the 

 termination being furnished with a valvular organization. 



The systemic heart is white and fleshy, and differs ac- 

 cording to the genera, in its form, being in the Octopus se- 

 micircular, but in the Loligo and Sepia lobed. Besides 

 giving rise to a large aorta, Qr principal artery, two smaller 

 ones likewise proceed from its cavity. These arteries are 

 furnished at their entrance with valves. 



The sexes in the Cephalopoda are distinct, the male and 

 female organs being found on different individuals. There 

 is not, however, any external mark by which they may be 

 distinguished. M. Cuvier found that the males of the Oc- 

 topus were scarcely a fiftn part so numerous as the females. 



The male organs of generation consist of the following 

 parts : The testicle is a large white glandular purse, con- 

 taining numerous fringed filaments, from which the seminal 

 fluid is secreted. This fluid passes out of the testicle by a 

 valvular opening, into the vas defer ens. This canal is slen- 

 der, and greatly twisted in its course, and opens into a ca- 

 vity which has been compared to the seminal vesicle. The 

 walls of this last cavity are strong and muscular, and dis- 

 posed in ridges. Near the opening at the distal extremity 

 of this sac is an aperture leading into an oblong glandular 



