BY E. J. GODDARD. 773 



ties, and the assistance gained from the study of an entire 

 specimen has been of little use in making the following brief 

 notes. One finds that this system suffers much damage when 

 the sections are injured in the process of cutting, on account of 

 the presence of siliceous material in the digestive tube, and 

 especially so as the vessels appear to have in their walls some- 

 thing of a chitinous nature, and the tortuous nature of the vessels 

 increases the difficulties attendant on a detailed reconstruction 

 of the system, the investigation of which would no doubt be much 

 facilitated by observations made on living specimens. 



There are present throughout the body a dorsal and a ventral 

 longitudinal vessel, the former much the larger and pursuing an 

 undulating course along the mid-dorsal line of the digestive canal; 

 the latter lying immediately above the ventral nerve-cord, and 

 pursuing a straight course. The dorsal trunk is locally dilated 

 in each of segments v.-x., and is constricted at each of the septa 

 separating these segments, so that, in an entire specimen, it 

 appears as a linear series of swollen loops, one in each of these 

 segments, above the digestive tube. In the first three segments 

 it is much narrower and pursues a straight course, but behind 

 these it follows a tortuous path, turning on itself in a sigmoid 

 fashion in each segment. In segment x., it turns towards the 

 ventral vessel in association with the deflection of the oesophagus 

 in this region, so as to lie in the centre of the body-cavity in 

 segment xi. In segment xii., it rises again to a more dorsal 

 situation as before. Immediately in front of the septum 

 separating segments i. and ii., it turns downwards to run under 

 the brain between that structure and the antero-dorsal wall of 

 the pharynx, emerging again in the midline on the antero-ventral 

 aspect of the brain between the oesophageal connectives, and 

 immediately bifurcates. The branches thus formed run off at 

 right angles to the stem, each in company with an oesophageal 

 nerve-connective; eventually they unite to form the ventral 

 vessel in segment iii., that is the segment behind that in which 

 lies the subcesophageal ganglion formed by the junction of the 

 oesophageal connectives. 



