CONTRIBUTIONS TO THE ANATOMY OF THE HIRUDINEA. 479 



remarkable structure in the whole group. It is a single con- 

 tinuous organ, a most marvellously complicated network of 

 tubules, communicating those on one side of the body with those 

 on the other, and continuous throughout the greater portion 

 of the body. 



The tubules lie inside the muscular layers of the body wall 

 and among the connective tissue and gland cells. They extend 

 as far forwards as the ninth nerve-ganglion, and as far back- 

 wards as the nineteenth (figs. 3 and 8), 



Internal Funnels. — There is a paired series of funnels 

 lying in the ten segments, 9 to 18 inclusive. These funnels 

 lie in the dorso-ventral blood sinuses (fig. 8, neph. fun.). 

 The funnel itself is composed of from four to six rounded cells 

 with large nuclei ; these cells are richly ciliated upon their free 

 surfaces, and surround the lumen (figs. 53, 54). The lumen of 

 the funnel often appears, however, to be occluded, its place 

 being occupied by a mass of vacuolated protoplasm (fig. 54, b.) > 

 the funnel does not probably possess much functional activity. 

 This occluding of the lumen is, as we shall see, carried to a 

 much greater extent in Hirudo. Following upon the funnel 

 itself is a short neck (fig. 54, a), presenting a large nucleus in 

 the wall and a ciliated lumen. This opens into a considerable 

 dilatation; the walls of this dilatation consist of numerous 

 flattened cells, and appear, together with the neck, to be 

 partially covered by an epithelium (1. c, ep.). 



1 have traced the communication of this dilatation with the 

 tubules in sections; it may, moreover, be sometimes seen in 

 fresh preparations (fig. 53, x). 



The dilatation has very curious contents, and appears at 

 times very much distended. As stated above, and as may be 

 seen from figs. 53 and 54, the whole apparatus, funnel and 

 dilatation, lies in a blood-sinus, in which float freely, blood- 

 corpuscles and coelomic epithelium - cells, and the ciliary 

 current carries corpuscles down the funnel from time to time. 

 These cannot apparently pass further, and lodge in the dilata- 

 tion. 



The contents seem to consist mainly of degenerating or 



VOL. XXIV. NEW SEa. K K 



