The anatomy of Lottia gigantea Gray. 



27 



C,i„Ai~- 



behind. From here the line of attachment turns again forward and 

 parallel to the curvature of the spindle muscle, to the corner of the 

 pericardium, following a course about one-third of the distance from 

 the upper edge of the shell muscle to the median line of attachment 

 (Z 1 ). It is obvious that the space between the membrane and the 

 muscular wall is the right kidney: that centrally between the two 

 parts of the membrane, 

 occupied mostly by the 

 gonad, is the coelom. 

 Vessels which reach 

 the edge of the gonad 

 (Y Figs. J, K and B), 

 and these include the 

 greater number, pass 

 directly into this mem- 

 brane just described 

 (X Fig. K), where they 

 intercommunicate and 

 course ventrad. Those 



of the right side 

 reach a median venous 

 sinus , which follows 

 the line of attachment 

 of the membrane along 

 its whole length, and 

 opens posteriorly into 

 a vessel leading through 

 the spindle muscle, 

 directly to the mantle 

 circulation (Med. S). 

 The blood in the small 

 portion of the mem- 

 brane on the left side of the body (X 1 ) enters mostly spaces lying 

 directly under the superficial layer of muscle on the floor of the 

 coelom, whence it reaches the median sinus. Some, however, works 

 backward through the inosculation of these veins in the membrane, 

 and reaches the median sinus near where it passes through the spindle 

 muscle. From these remarks it is evident that the greater part of 

 the blood from the gonad reaches the mantle circulation without en- 

 tering the vascular network over the dorsum of the nephridium, 



Fig. J. Gonad, with alimentary system removed, viewed 

 from above to show branching of genital artery (Gen. A). 

 XX showing a few vessels passing into vein-net of kidney, 

 Y, Y place where vessels leave gonad and pass into mem- 

 branes (Fig. K) separating gonad from right kidney. 



