Benham. — On Earthicorms. 



139 



and concludes that it is a variety of the Japanese species. 

 I cannot but think that his decision would have been different 

 had he had a greater number of and better-preserved specimens 

 at his disposal. Nevertheless, he recognises certain differences; 

 chief amongst them being the presence in the Chatham Islands 

 worm of preclitellian tubercles, in addition to the postcli- 

 tellian tubercle (on 19/20). These he places at 11/12, 12/13 r 

 and 14/15, but remarks that they are " undeutlicher umwan- 

 dete." In all the nineteen mature specimens in my posses- 

 sion, collected by two different persons at different times and 

 probably at different spots, the tubercles are extremely well 

 defined, having an oval margin well raised up from the sur- 

 rounding skin ; and, while presenting the first two tubercles 

 (on 11/12 and 12/13), not one of them shows a trace of any 

 similar structure at 14/15. Michaelsen is so experienced and 

 so careful an observer that this discrepancy can only be due 

 to the imperfect condition of his specimen ; he has, I fancy, 

 mistaken for an incipient intersegmental tubercle a transverse 

 glandular ridge, which in most of my specimens exists on seg- 

 ment 14 between the ventral chaetae of the two sides. A simi- 

 lar more or less swollen ridge occurs, in several of my speci- 

 mens, also on segments 15 and 16. But these are quite dif- 

 ferent in structure and in position from the intersegmental 

 tubercles. Another point upon which my specimens disagree 

 with his is in reference to the prostomium, for he states, " Der 

 Kopflappen ist quer oval, vom Kopfring scharf abgesetzt, tend 

 Uisst keine Spur eines dorsalen Fortsatzes erkennen." This is- 

 the more curious in that the Japanese species has this pro- 

 cess, where, however, it reaches back to the hinder edge of 

 the buccal segment. 



A comparison of the Chatham Islands worm, as repre- 

 sented by my collection, with the Japanese species shows the 

 following more or less important differences : — 



Dimen- 

 sions. 



nfeftsJ Clitellum. 



Sperniathecse. 



Sperniiducal 

 Gland. 



90-110 mm. 



by 

 3-35 mm. 



100-105 



P. matsushimensis. 



12-17 

 (complete) 



19/20 



Diverticulum rather 

 shorter than sac, 

 which has no dis- 

 tinct duct 



Much coiled ; 

 ext en ding 

 through seg- 

 ments 17 to 

 19, with long 

 duct in 17 

 and 18. 



