88 WILLIAM BLAXLAND BENHAM. 



filled with a white granular substance similar to that found in 

 the nephridial vesicles ; this rounded end is directed outwards, 

 whilst the narrow duct passes at first inwards, then bends back- 

 wards and pierces the body wall. By means of transverse 

 sections the external aperture of these organs is found to be 

 situated between the nerve-cord and the ventral couple of 

 setse on each side (fig. 20, b). They were not sufficiently well 

 preserved to make out any details of their structure, but, so far 

 as I could make out, their general structure is as follows : — 

 A delicate membrane surrounds the sac (fig. 21, a) and forms its 

 wall, within which is a granular substance [b) which was stained 

 only slightly by borax-carmine. In the centre of this substance 

 is an irregular lumen [d) lined by short columnar cells (c) 

 whose nuclei stained deeply ; whether these are ciliated or not 

 I was unable to determine. 



The diagram (fig. 20) shows the position in relation to the 

 setse of this pyriform sac and its pore on one side, and the 

 nephridiopore on the other side. 



These pyriform sacs seem quite similar in shape and position 

 to those found only in the posterior region of the body in 

 Urochseta; what their function maybe seems quite impos- 

 sible to say at present. 



The vascular system was not followed to any great ex- 

 tent. The dorsal trunk (fig. 14, jo) is ampullate posteriorly and 

 becomes wider in the region of the pouched intestine ; passing 

 forwards this character becomes more marked in somites xiii 

 and forwards. In the intestinal region a pair of vessels is 

 given oflF in each somite to the intestine. In each of the 

 somites xii and xiii is a pair of moniliform lateral hearts, 

 but anteriorly to these somites these hearts are very thin and no 

 longer moniliform ; they pass from the dorsal to the ventral 

 trunk. Beside the dorsal and ventral trunks both a typhlosolar 

 and a subneural trunk are present. 



The nervous system exhibits no essential difi'erence from 

 that of Lumbricus. The cerebral ganglia are distinct and 

 placed in somite iii. 



Thus Urobenus resembles Urochaeta in two remarkable 



