60 Girynnetlt Bncluinaa : 



specially selected on account of the double dorsal vessel in C. 

 gippslandicus, and of the large vessels in F. unicus, which 

 made the structure of valves, etc., easier to make out in detail. 

 Of course it is very hard, even with a dissecting microscope, 

 to make out some of the very fine connections (especially with- 

 out the aid of living specimens, which might be injected), and 

 a later examination which I hope soon to undertake with the 

 aid of serial sections, may disclose junctions between vessels not 

 noticeable before, or their absence, where they were thought 

 to exist — for instance, in the relation between the dorsal and 

 ventral vessel in the first and last segments ; and the method 

 of ending of the supra and subintestinal at the anterior end. 

 Bourne (11) in his paper on MegascoJex cocrul pah^ describes the 

 dorsal vessel as ending abruptly at the posterior end, and 

 breaking up at the anterior, while he states that Jacquet figures 

 peripharyngeal commissures between the dorsal and ventral 

 vessels, sometimes as very fine threads, so that the presence or 

 absence of this connection is apparently not a constant feature. 



Xomenclatui'e of Vessels. 



The accompanying diagrams (Plate XYI.. Figs. A, !>, C, D) 

 will serve to indicate the nomenclature of the blood vessels that 

 I propose to employ during the course of this investigation. 



In none of the worms examined have I found a subneural 

 vessel. Bourne (11) says this is absent in all the simpler, and 

 many of the more complex forms, e.g., many, if not all, the 

 Perichaetidae, Pontodrilus and Microcliaeta He uses the 

 term " ventral " for the subintestinal which, he saj's, is con- 

 stant in all Oligochaetes, evidently meaning the main ventral 

 vessel of Australian forms, and not that which I have called 

 Bubintestinal. This latter, together with my lateral, forms 

 what he calls the Intestino-tegumentary vessels of Perrit'r 

 (Reel), pour servir al' hist, des Lon)briciens terrestres," Nouv. 

 Arch, du Mus. d'Hist. Nat. de Paris, 1872), or his latero-longi- 

 tudinal vessels, which, he says, are exaggerated anterior repre- 

 sentatives of a series of similar vessels, which occur in every 

 segment, and to which whole series he gives the name intestino- 

 tegumentary. He defines Hearts as those vessels which are 



