1907.] ON NEW SPECIES OF AFRICAN OLIGOCH^TE WORMS. 277 



5. On Two new Species of the African Grenus Microchcetus 

 belonging to the Collection of Oligochyeta in the Museum 

 of Christiania. By Frank E. Beddaed, M.A., F.R.S., 

 Prosector to the Society. 



[Received Februaiy 1, 1907.] 



(Text-figures 85 & 86.) 



Dr. Robert Collett, the well-known chief official of the Christiania 

 Museum, was so good as to entrust me, some little time since, 

 with the collection of Oligochteta belonging to that Museum for 

 study and description. In examining the collection I found 

 three specimens, representing two species, of the Ethiopian genus 

 Mici-ochcetus* which I believe to be new to science, and of which 

 1 beg to lay the following descriptions before the Society. 



MiCROCHJETUS COLLETTI, Sp. n. 



I have the pleasure of dedicating this obviously new species to 

 Dr. Collett. The material consists of but one specimen, which is 

 entire, but considerably softened. It measures about 170 mm. 

 in length by 7 mm. in breadth after the clitellum ; the anterior 

 region of the body is wider. The colour is grey-brown, yellow 

 on the clitellum. 



The setce have the usual paired arrangement found in this 

 genus, and commence upon the second segment of the body. The 

 setse are smaller upon the anterior segments and considerably 

 lai-ger in the clitellar region, where they are quite twice the 

 length. The larger setae are ornamented. Some of the anterior 

 segments consist of two rings. 



The clitellum (text-fig. 85) is very sharply marked off by its 

 colour and by the greater thickness of the body-wall in this 

 region. It commences with the xivth and ends with the xxivth 

 segment. The position of the clitellum is not anomalous for the 

 genus, and the specimen permits of no doubt upon the matter. 

 The clitellum is perhaps best described as " saddle-shaped " ; but, 

 as a matter of fact, the clitellar epithelium has also invaded the 

 ventral surface. There is, however, a diminution in thickness 

 indicated by an overhanging of the body- wall just ventral wards 

 of the lateral setse. This arrangement is interfered with in the 

 region of the genital papillae by those structures, as will be seen 

 by the accompanying figure (text-fig. 85). 



The nepliridiopores are obvious and in front of the lateral pair 

 of setge. 



The oviducal pores are very conspicuous upon the xivth segment. 

 Each lies between and in the same line with the ventral and 

 dorsal setae. 



* In addition to the species known up to the end of last century (see Michaelsen, 

 Oligochaeta in ' Das Thierreich '), M. griseus has been subsequently described (see 

 Michaelsen, MT. Mus. Hamburg, xix. 1904). 



