260 SUBANTARCTIC ISLANDS OF NEW ZEALAND. [Oligochaeta. 



proximal ' region, where they resemble the higher cells of the globular sac, which 

 corresponds to the diverticulum of higher worms. This sac has an epithelium of tall 

 gland-cells, and the whole organ is enveloped in a thin muscular coat. 



The ampulla is filled with spermatozoa, without any arrangement or order : 

 but in the glolnilar sac the sperms are orientated, so that the heads are towards the 

 epithelial cells, and it appears that each cell has many sperms associated with its 

 end. Hence I conclude that spermatophores are formed. 



Localiti/. — Auckland Islands (Erebus Cove, in Port Ross). Under stones on the 

 sea-shore. 



Reiuarks. — The only genus that has a sperm-duct covered with gland-cells, and 

 is of short extent without any convolutions, is Rhizodrikis. It appears to me that 

 the brief diagnosis of Monopylephorus given given by Levinsen* is insuiBcient to 

 enable one to identify his worm. Beddard and Michaelsen, in their systematic 

 treatises, have regarded it as, possibly, synonymous with Stoic's Bothrioneuron ; 

 while Ditlevsenf believes it to be identical with Goodrich's V ertnicAilus\. as he found 

 this worm (F. filosus) in abundance on the stretch of shore on which Levinsen col- 

 lected his M. ruhroniveus. 



In view of the meagre diagnosis given by Levinsen, one is still in doubt as to 

 whether this is the case, and it seems to me better, and more in accordance with a 

 common - sense interpretation of the Rules of Nomenclature, to place Levinsen's 

 generic name as a nomen nudum. 



There may be a great probability that Monopylephorus ruhroniveus is identical 

 with Vermiculus pilosus, but, as all sorts of changes in environment lead to disap- 

 pearances of worms from a given locality, this is by no means beyond the region of 

 doubt. Then, since Vermiculus was used by Dalyell {fide Michaelsen)'for a Nematode, 

 we must fall back on Smith's generic name, Rhizodrilus. 



The present species differs from the other species of the genus in the wide 

 separation of the paired pores of sperm-duct and spermathecae, for in all but 

 R. trichochaetus, Ditl., these organs open by median pores — that is, into a median 

 invagination of the epidermis — which Goodrich has shown to be a secondary con- 

 dition, attained at maturity. The new worm also differs in having a distinct penis. 



In R. limosus, Hatai§, and R. glaher, Moore||, the lower end of the sperm-duet 

 is widened out to form an atrium, but there appears to be no penial sac or penis 

 in any of the species, though one regrets that Ditlevsen has not given more details 

 about R. trichochaetus. Moore speaks of R. glaher having an " eversible median 

 bursa which probably acts to some extent as a substitute for a penis." 



The seven species hitherto described have been found in Europe and North 

 America (east coast). It is therefore difficult to explain the presence of the genus 

 in these antipodal shores ; but, as practically nothing is known of the " Microdrili '' 

 of places outside these two continents, no suggestion as to the manner of the occur- 

 rence here is possible. 



* Levinsen, iii Vid. Medd. Nat. Poren., 1883. 

 t Ditlevsen, Zeit. fur Wiss. Zool., Ixxvii, p. 423, 1904. 



+ Goodrich, Zool. Anz., xv, p. 476, 1892 ; and Quart. Journ. Micr. Sei.. xxxvii, p. 253, 1895. 

 § Hatai, " On Verm.iculus limosus,''' Annot. Zool. Japon., ii, p. 103, 1898. 



I| Moore, " Some Marine Oligochaeta of New England," Proc. Acad. Nat. Sci., Philadelphia, 1905, 

 378. 



