ON STYLOCHUS PELAGICUS. 25 



the exterior and by -which the pharynx is extruded is nearly 

 central in position. The intestine presents the usual niiilti- 

 ramified arrangement, there being eight pairs of primary 

 branches and one anterior median, which as usual passes 

 over the cephalic ganglia and divides into three secondary 

 branches. There is no anastomosis between any of the 

 branches, not even between the most posterior pair, although 

 each member of this pair gives ofiF a short transverse branch 

 directed inwards towards the middle line. 



The cephalic ganglia are large and distinct, of the same 

 form as in Leptoplana tremellai'is, and of similar structure, 

 the transverse commisural fibres being very well defined ; 

 the main nerve trunks are distributed in the usual manner, 

 a pair of especially stout ones going to supply the posterior 

 part of the body. 



The eye spots, which are intensely black, are disposed in 

 two pairs of groups situate in front and behind the ganglia 

 respectively (Plate III, fig. 10), the anterior group being the 

 largest, and in a pair of rings which encircle the bases of the 

 tentacles. The tentacles have no eyes on their tips or sides ; 

 they are situate just in front of the junction of the anterior 

 with the median third of the body. The water vascular 

 system is extremely well seen, the fine peripheral trans- 

 lucent network being clearly defined when the animal is 

 viewed by transmitted light. I could distinguish no openings 

 of the system to the exterior. 



The generative organs occupy an elongate space situate 

 immediately behind the mouth (Plate III, fig. 9). The male 

 organs consist of testis, vesicula seminalis, prostate and penis 

 (Plate III, fig. 11). The testes are narrow and tortuous in 

 outline, and commencing on each side at the level of the 

 hinder margin of the sheath of the pharynx, come back- 

 wards as far as the anterior generative opening. The vasa 

 deferentia pass almost transversely inwards, presenting at 

 their commencement a sudden but short twist upwards, 

 forming a small loop. This loop at the commencement of 

 the vasa deferentia is present in very many Planarians, and 

 persist even in the Landplatiarians Bipalium and Ryncho- 

 demus. The vasa deferentia open into a mesially placed 

 ovoid vesicula seminalis, beneath which is an ovoid glandular 

 cavity, from which proceeds a wide strongly muscular duct, 

 tortuous in its course in the retracted condition of the penis, 

 and which terminates in the cavity of that organ. 



The penis itself as seen in the retracted condition and as 

 figured in Plate III, fig. 11, has the shape of a cone with a 

 truncated apex. It is contained in a spacious flask-shaped 



