SEA-FISHERIES LABORATORY. '241 



vessel (figs. 23, 36). This is usually first distinguish- 

 able posteriorly about the middle region of the stomach, 

 and becomes more clearly differentiated as it proceeds 

 forwards. Each receives blood from the dorsal and sub- 

 intestinal vessels through the gastric plexus, and opens 

 into the auricle, which is a thin walled expansion, 

 probably of the gastric vessel. 



After giving off the lateral oesophageal vessel, the 

 auricle opens into the ventricle, the Avails of which are 

 muscular, and drive the blood into the ventral vessel. 

 The lateral oesophageal vessel on each side gives off a 

 branch to the oesophageal pouch, and then runs forward, 

 supplying the lateral walls of the oesophagus, and breaks 

 up into capillaries between the first and second 

 diaphragms. 



On each side of the nerve cord there is a small vessel 

 which accompanies the cord along the whole length of the 

 body. These neural vessels arise in front in the triangular 

 area between the oesophageal connectives by union of 

 capillaries from that region. Branches of the ventral 

 vessel enter into connection with them in the five segments 

 (second to sixth inclusive). 



The vessels of the body wall are well developed 

 (figs. 24, 3G). There are on each side two longitudinal 

 vessels distinguishable from the other vessels of the body 

 wall by their somewhat greater size— (1) the nephridial 

 longitudinal vessel which runs on the inner face of the 

 body wall just ventral to the level of the nephridiopores, 

 and (2) the more obvious and more important dorsal longi- 

 tudinal vessel which runs parallel to but above the former, 

 being slightly dorsal to the level of the notopodial setal 

 sacs. The former (the nephridial longitudinal vessel) is 

 only well marked in and for a short distance anterior and 

 posterior to the nephridial region. The dorsal longitu- 



