190 ON A COLLECTION OF EARTHWORMS FROM NEW BRITAIN, THE 



subdivided more coarsely and then more finely. The ultimate lobules are very minute. 

 The duct of the gland, which is unprovided with a terminal sac, arises from the 

 posterior margin of the anterior of the three lobes. The spermathecae (Fig. 5) are five 

 pairs in segments V — IX. They are pear-shaped with a longish but narrow diverticulum 

 which is about half the length of the pouch. 



In the same tube which contained the worms from Narowol were a number of 

 smaller worms, of which two were larger than the rest, and mature. In spite of the 

 superficial likenesses of these to the ones that have just been described, I was at 

 first disposed to place them in a different species on account of their smaller size. 

 They are slender worms, the largest being 113 mm. long with a diameter of 3 — 4 mm. 

 The number of segments in this specimen was 100. The colour is the same as in 

 the typical Perichaeta solumonis. The genital papillae, however, differ in detail. But 

 they present a general similarity of arrangement. In the 1 u ger of the two specimens 

 now under consideration the papillae were fewer than in the smaller individual. In 

 the latter are a pair of papillae on each of segments XVII — XIX, corresponding in 

 position to the male pores. The XlXth has in addition a median papilla and on 

 segment XVIII are a pair of such papillae. 



On segment IX there are three median papillae. The clitellum is rather defective, 

 occupying segments XIV — XVI, and setae are present on the first and last of these 

 segments. The internal organs correspond in every detail to those of the typical 

 Perichaeta solomonis save that the muscular bands tying the gizzard to the parietes 

 are wanting. 



Is this to be regarded as a dwarf variety which, on account of its small size, 

 has not area sufficient for the development of the full complement of papillae ? I am 

 inclined not to take this view, and mainly for the following reasons. Among the 

 smaller worms contained in the tube were two or three which I consider to be 

 immature forms of the typical Perichaeta solomonis. It is of course impossible to be 

 certain upon this point; their very immaturity is in the way of arriving at a definite 

 conclusion. Now these presumed immature forms of the typical Perichaeta solomonis 

 have the robust form of the type and not the slender form of the variety which I 

 am now considering. There would seem therefore to be more difference between the 

 two varieties than a mere precocious development of the sexual organs. Yet the close 

 similarity of colour and the identity of internal structure must be borne in mind in 

 coming to a conclusion. I am inclined to look upon these slender examples of the 

 typical Perichaeta solomonis as individuals which represent a new species in the course 

 of differentiation ; the modification has advanced to a certain extent in certain of 

 the external characteristics but has not yet touched the internal organs. 



Perichaeta Pactfica, n. sp. 



Dr Willey's collection contains a considerable number of examples of a small 

 Perichaeta which I refer to a new species. 



One of these specimens was much larger than the rest, which were all small. 



