450 PROCEEDINGS OF THE ACADEMY OF [1894. 



The vascular system presents the usual supra-intestinal vessel with 

 its anterior portion modified to form a heart, a supra-neural vessel, a 

 peri-enteric blood sinus, four pairs of vascular arches in the head, 

 one pair each in the 1st and Vllth post-cephalic somites, and one 

 pair uniting the longitudinal trunks posteriorly in the IXth and Xth 

 somites. Two pairs of cephalic, and eight or ten of caudal, adhesive 

 glands are present, as well as circum-oral and hypodermal mucous 

 glands. An inconspicuous clitelluni is developed on somites VI and 

 VII. No salivary gland, such as is found in Bdellodrilus illumina- 

 tus, is present. 



Regarding the function of the dorsal organs there is little to say. 

 A priori one would expect them to be respiratory, but the apparent 

 entire absence of bloodvessels, which are unrevealed after a careful 

 study of sections, would tend to throw strong doubt upon such an 

 interpretation. Irregular spaces are evident here and there between 

 the muscle fibres, but these appear to be continuous with the inter- 

 muscular spaces which are developed betweeu the circular and longi- 

 tudinal muscle fibres of the body walls, and have not been traced 

 into any communication with the body cavity. Until an opportunity 

 is afforded of studying living examples in their proper habitat, and 

 observing the uses to which these organs are put, no opinion can be 

 vouchsafed. 



The two species are ot relatively minute size, and were at first re- 

 garded as larval stages of another Discodrilid, until sections revealed 

 the presence of perfectly mature spermatozoa and ova, some of which 

 latter were in the course of extrusion through the ovipores. 



Pterodrilus alcicornus sp. nov. 



PI. XIII, fig. 1, profile of entire animal, from a mounted specimen 

 about half extended, showing also the course of the alimentary 

 canal, the spermatheca, atrium, and vasa deferentia, the position 

 of the ovary and ovipores of the right side, and the dorsal gland in 

 the Vlllth somite. X 145. 



Fig. 1«, one of the jaws. X 640. 



Fig. 16, transverse section through the anterior part of the Vlllth, 

 post-cephalic somite, passing obliquely into the ventral part of the 

 Vllth ; the ovary is cut on one side, and the muscular septum 

 on the other; the intestine and nerve cord are shown ; a, intermus- 

 cular space. X 200. 



