Australian Earthvjorwis. 81 



figures an infra-intestinal vessel, and Beddard (2) describes a 

 single sub-oesophageal vessel in Acanthodrilus, while in 

 Typhaeus gemmii (3) he mentions the lateral, which supply 

 the gizzard, and run below the intestine close to each other ; 

 so that the single or double character of the sub-intestinal 

 is evidently a variable feature. 



7. There seems to be no evidence in Australian forms of the 

 existence of the subneural vessel. Beddard (2), in reference to 

 this structure, says (p. 473), '' The subneural blood-vessel, which 

 does not appear to be present in any genera of Oligochaeta, 

 which have been referred to Claparede's division of the 

 Limicolae, is also wanting in some earthworms. Perrier has 

 denied its existence in Portodrilus and Perichaeta, and Benham 

 states it is also absent in Microchneta. It is therefore of sonxe 

 little importance to note that this blood vessel is not in- 

 variably absent in the genus Perichaetay 



8. That the general rule is for the dorsal to be a single 

 vessel, and that even where it is double, as in M. goonmurk 

 and C. gippslandicus the ventral is single. Beddard (4), quot- 

 ing from Balfour, Comparative Embryology, vol. i., p. 282, 

 says that the existence of a double dorsal vessel seems an 

 embryonic character, because the single vessel in Lumbricus 

 and Criodrilus is formed by coalescence of two vessels at first 

 distinct. In the same paper he describes the double vessel in 

 Microcliaeta rappi ; and in (2) one in Acanthodrilus annec- 

 tens: iihoin AcantJindrihis antarcticus {3). There are many otiier 

 recorded examples, e.g., Benham (7) in Microcliaeta papillata ; 

 Acanthodrilus haplocrystis (8) ; at the anterior end of Pleu- 

 rochaeta (9) ; in Dinodrilus heddardi (10) ; and others, e.g.. 

 Bourne (11). 



9. That the blood supply to the alimentary canal and 

 related structures at the anterior end is generally more or less 

 in the form of a plexus (compare Bourne, 11), which may be 

 associated with the much-divided structure of the salivary 

 gland. At the hinder end the supply is simple, being mainly 

 from the conimissural vessels. 



