192 ON A COLLECTION OF EARTHWORMS FROM NEW BRITAIN, THE 



in P. perkmsi 1 . He suggests that this may not be an unusual occurrence in the 

 genus Perichaeta. It is at any rate not universal, for I have examined from this 

 point of view the Bermudan species P. bermudensis in which I find that the sperm 

 ducts open into the duct of the spermiducal gland before it acquires its thick muscular 

 coat. 



The most salient structural feature of this Perichaeta is the presence of only a 

 single pair of sperm sacs to which correspond but a single pair of testes and sperm 

 ducts. Dr Rosa has pointed out that at present this character — the possession of 

 only a single pair of sperm sacs — characterises nearly all the species of the genus 

 from New Zealand. It is to be seen in P. forbesi, F. E. B., P. neoguinensis, Mich., 

 and in P. loriae and P. papua of Rosa. In a specimen of Perichaeta however, not 

 identified, from New Guinea, Rosa did not find that characteristic feature ; that Peri- 

 chaeta had the usual two pairs of sperm sacs. It is therefore important clearly to 

 distinguish the present species, which is not widely separated in geographical range 

 from any of those forms. It will be apparent I trust from the foregoing description 

 that Perichaeta pacifica cannot be confounded with any of the above mentioned 

 species. I imagine that it will be found when those species are more fully investi- 

 gated that they will prove like P. pacifica to possess only a single pair of testes and 

 funnels. 



PONTODRILUS MaTSCTSHIMENSIS, Iizuka. 



P. -matsushimensis, Iizuka, Annotationes Zool. Japon. II., Pt. i., p. 21. 



Dr Willey collected a large number of a species of Pontodrilus on the shore of 

 the Isle of Pines which I identify with the above named species of the genus. That 

 species is a native of the Japanese shores, having been met with there and described 

 by Akira Iizuka. The fulness of Mr Iizuka's description renders it unnecessary for 

 me to give an attempt at a complete account of the characters of the worm ; but 

 there are some points about the species which require a few notes. 



The describer of the species does not comment upon the setae — as to whether 

 they are or are not ornamented. This character is known to distinguish one species of 

 the genus, viz. P. bermudensis- . I do not find any ornamentation ; for this reason and 

 for the fact that the thickened septa extend from segments V to XIII, the present 

 form from the Isle of Pines cannot be the same as P. bermudensis. In the latter 

 species the thickened septa extend from segments IV to XI. 



In my specimens however the clitellum is not quite so extensive as it is described 

 to be by Iizuka. He states that it comprises segments XII — XVII; but in the 

 plate it is represented as extending over segments XIII — XVII only (the oviducal 

 pores being wrongly assigned to segment XIII). This is precisely what I found in 

 Dr Willey's examples. Furthermore the oviducal pores lie a little to the inside and 



1 On some Earthworms from the Sandwich Islands, &c, P. Z. S., 1896, p. 200. 



2 Pontodrilus arenae of Michaelsen : Terricolen der Berliner Zoologischen Sammlung, Arch. f. Naturg., 1892. 



