638 WILLIAM A. HASWELL. 



Excretory System, — There are two excretory apertures 

 (fig. 1, ex.) situated on the ventral surface, just behind the 

 ventral diverticulum of the intestine, and immediately external 

 to the main nerve-cord. Each leads into a tubular sac with 

 thick walls, and lined with a thick layer in which nuclei are 

 not visible, though doubtless it is of the nature of an ecto- 

 dermal epithelium. Spaces similar to those in the epidermis 

 occur at intervals ; and in the interior of the sac is a quantity 

 of fibrillated substance, which may partly be the remnants of 

 cilia, though of this there is no positive evidence. From this 

 excretory sac runs dorsad a sinuous canal, which bifurcates to 

 form an anterior and a posterior longitudinal trunk. The 

 former is the smaller. It runs forwards, external and dorsal 

 to the larger nerve-cord, to the anterior extremity of the body, 

 where in the neighbourhood of the ciliated sac it becomes 

 somewhat dilated and much convoluted. Its continuation, or 

 a branch, passes transversely in front of the brain, but is not 

 traceable as far as the middle line. The posterior longitudinal 

 trunk is very wide, and, like the anterior, twists about in a 

 sinuous manner. Some distance back it bifurcates, the two 

 branches running back side by side for some distance. Both 

 anterior and posterior trunks give off numerous branches. 

 At some points they seem to unite for a short distance and 

 diverge again. 



In the main the disposition of the parts of the excretory 

 system resembles that of the corresponding parts in Pro- 

 rhynchus, as described by Schultze, v. Graff, and others ; but 

 there are some important points of difference. The position 

 of the external openings is the same in both, and in both the 

 short vessel into which the aperture leads bifurcates to form 

 anterior and posterior trunks; but in Prorhynchus the 

 posterior trunk does not bifurcate, and an internal longitu- 

 dinal vessel running through the entire length of the body is 

 given off from a transverse commissural vessel situated far 

 forwards. 



Reproductive Apparatus. — The organs of the two sexes 

 are both mature in three out of the four specimens. The male 



