128 MOLLUSCA. 
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, or 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 fifth part so numerous as the females. 
The male organs of generation consist of the following 
parts: The ¢esticle 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 deferens. ‘This canal is slen- 
der, and greatly twisted in its course, and opens into a ca- 
vity which has been compared to the sem¢nal 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 
