F. M. 7)(r/)bi«U — Anotomy <in<] Ilahits of N'erels virens. 275 



moving in a series of waves toward the liead. The ventral vessel 

 sends oif, in each segment of the body, except a few in the region of 

 the proboscis, two smaller vessels, one on each side. These two ves- 

 sels fork, each sending a branch to the inferior ramus of the foot of 

 the next segment to the rear (tigs. 20-24, /"), and another larger 

 branch ic) around the intestine, by the side of the transverse parti- 

 tion, to the dorsal vessel, receiving, also, on its vvay, a vessel from 

 the upper ramus of the foot of its own segment {d). Jiesides these 

 principal lateral vessels, there are five other vessels on each side in 

 each segment, coming from the ventral vessel (iig. 20). These form 

 a loose but regular network that surrounds the intestine and is 

 connected with live other convoluted vessels, which join the dorsal 

 vessel. This network on the intestine probably supplies the hepatic 

 organ with material for its secretion, and very likely may receive 

 nutritive material from the digested food. The blood moves in 

 waves, at regular intervals, through the peripheral vessels (figs. 20- 

 24, c) to the dorsal vessel, but I could not see in which direction the 

 blood moved in the network. The blood is forced into it at each pul- 

 sation of the dorsal vessel, l)ut the normal flow may be in the opposite 

 direction. The peiipheral vessels are also connected with this network 

 (tig. 20). The dorsal and ventral vessels are connected at the posterior 

 extremity of the body by a simple peripheral vascular ring (fig. 23, c), 

 in which the blood flows from the ventral to the dorsal vessel. In 

 the region of the proboscis, the ventral vessel sends lateral branches 

 directly to all the feet but the first three (figs. 20 and 21). It then 

 sends a pair of vessels to the oesophagus (figs. 20 and 21, e), which 

 pass back along the oesophagus, one on each side, as far as the intestine, 

 being connected with smaller vessels on the surface of the oesophagus. 

 The ventral vessel next sends otf a pair of vessels which expand into 

 capillary networks, one on each side (figs. 20, 21, s and g). Each of 

 these networks sends small branches to the first three feet on its 

 own side, and then merges into a vessel (figs. 20 and 21, A), which 

 goes to the base of the tentacular cirri. The ventral vessel now goes 

 upward to the under surface of the proboscis, and there divides into 

 three branches (figs. 20, 21, t, t and /). The middle branch (fig. 21, 1) 

 passes under a muscle and along the median line of the ventral sur- 

 face, as tar as the pharynx, where it divides into two, forming a small 

 vascular ring (fig. 21, n) about the latter. The two lateral branches 

 pass upward and backward on the proboscis, each expanding 

 into a remarkably rich and delicate network on its own side of the 

 proboscis (figs. 20 and 21 , u). From each of these networks a vessel 



