26 WALTER K. FISHER, 



liver and over the stomach and rectum. All the blood passes into 

 vessels of the right kidney, to be detailed more fully under the venous 

 circulation. The ventral branch (V.Br) also divides into numerous 

 branches which course backward, anteriorly, upward and downward. 

 The main posterior branch supplies chiefly the under side of the 

 stomach, intestine, and liver. Certain branches pass under the stomach 

 and over the distal limb of the intestine directly into the kidney 

 network. Anterior branches supply the several coils of the intestine 

 in that portion of the visceral mass and are better understood from 

 the figure than from descriptions. The dorsal branch shown in this 

 figure in deep red, arises from the anterior portion of the visceral 

 artery and courses directly upward to supply the under surface of 

 the anterior loop of the stomach and a loop of the intestine (Fig. 1, 

 blue) lying under the stomach and rectum. From the curvature in 

 front of the proventriculus the main artery turns directly forward and 

 rises so that it comes to lie considerably above the level of the left 

 portion. Just before joining the funnel-shaped opening from the head 

 cavity the artery bends sharply downward. Putting the same fact 

 conversely, the right limb of the visceral artery on leaving the com- 

 mon opening from the buccal sinus turns sharply upward, then back- 

 ward. 



The genital artery or posterior aorta, whichever one may choose 

 to call it, passes from the outer posterior corner of the pericardium, 

 turns downward and enters the gonad (Figs. 1 and J Gen. A). Here 

 a division into anterior and posterior portions takes place, and each 

 of these divides into a varying number of branches. The ultimate 

 ramification results in very fine vessels, permeating every part of the 

 gonad, and forming an intricate network, in and about the lobes and 

 lobules of the gland, which would be difficult to show in a drawing. 

 All the blood reaches the mantle circulation but by two different 

 routes. A very small portion passes through slender vessels, the final 

 branches of those lying nearest the upper surface of the gonad 

 (Fig. J XX), directly into the venous meshwork of the kidney. To 

 understand the course of the remainder it will be necessary to turn 

 aside for a moment. The cavity of the coelom, or secondary body 

 cavity, in which jthe gonad lies is separated from the large right 

 kidney space by a prominent membrane. This is attached to the 

 muscles of the floor of the hollow in which all the organs lie, along 

 the median line (Z Figs. B and K), from the boundary of the buccal 

 sinus in front nearly to the attachment surface of the spindle muscle 



