OLIGOCHAETA 



PART II. EARTHWORMS 

 By Grace E. Pickford, Ph.D. 



Osborn Zoological Laboratory, Yale University 



(Text-figs. 1-3) 



INTRODUCTION 



TH E collection of earthworms made by the Discovery Expedition comprises fifteen 

 species from five major localities, viz. the islands of Annobon in the Gulf of Guinea, 

 Tristan da Cunha, South Georgia, the Falkland Islands and Hermite Island, Cape Horn. 



From Annobon only one species was obtained, Dichogoster bolaid var. ; it is not the 

 same as the form of this species previously recorded from the island (see p. 287), but 

 since this species is a peregrine of wide distribution in warm countries there is nothing 

 remarkable in this. Apparently no other species of earthworm has so far been recorded 

 from Annobon. 



From Tristan da Cunha only five peregrine Lumbricids were obtained ; this is to be 

 expected from a volcanic, oceanic island. It is interesting to find that one of these 

 species, Lumbricus rubelliis, apparently forms a distinct race on the island (see p. 289). 

 In the collection of the South African Museum, Cape Town, there are specimens from 

 Tristan da Cunha (examined by myself) of two of the species here recorded, viz. 

 Allolobophora caliginosa and Lumbricus rubellus. Apparently no other collections of 

 earthworms from the island have as yet been examined. 



From the island of South Georgia only one species is recorded, Microscolex georgiamis; 

 this species occurred abundantly in the collections made by the Discovery Expedition 

 in various parts of the island. This species is endemic to South Georgia, but is closely 

 allied to species from the Falkland Islands (a variety, var. laevis, is described by Rosa^ 

 from Patagonia, but is of doubtful status). An extremely interesting new form of 

 M. georgianus occurred together with the typical form from one locality in the present 

 collections; in this form microscolecine reduction has occurred without affecting any 

 other characters. 



From the Falkland Islands two endemic species of Microscolex, and two peregrine 

 Lumbricids, viz. Dendrobaena siibrubicunda and Bimastus tenuis, were found in the 

 present collections. The latter are of especial interest in that they both show a pecuhar 

 restriction of the gizzard to segment 17. Michaelsen^ has previously recorded D. sub- 

 rubicunda from this locality, but does not comment on the position of the gizzard. Of 



1 Rosa, Atti. Soc. Modena (4), iv, p. 9. 



2 Michaelsen, W., Ergeb. Hamb. Magalh. Sammelr., Terricolen (Nachtrag), p. 27. 



