THE 0LIG0CH.1^]TA OP NATAL AND ZULULAND. 448 



dorsal distance is distinctly smaller than half the circum- 

 ference, at least at the middle and hinder portions of the body. 

 It is difficult to see the condition in the front portion, as the 

 type-specimen is dissected and the body-wall is irregularly 

 stretched {dd = circa f u) . 



Copulatory papillae : the ventral pairs of setas of the tenth, 

 eleventh, twelfth and twenty-fourth segments are placed 

 upon the top of copulatory papillae. The papillte of the tenth, 

 eleventh and twenty-fourth segments are distinct, but those 

 of the twelfth segment are less obvious. 



Internal Anatomy. — Sexual seise : I have examined the 

 sexual (ventral) sette of the twelfth and tAventy-fourth seg- 

 ments ; those of the twelfth segment have a length of 0*6 mm. 

 and a maximum diameter of 32 /i, Avhile those of the twenty- 

 fourth segment are nearly twice as large, being about 1*0 mm. 

 in length and 60 fx in maximum diameter. They are both 

 sigmoid, and are pi-ovided with a distinct but not sharply 

 bordered nodulus. They terminate in a simple point. With 

 the exception of the extreme tip the distal third of the seta 

 shows a fine ornamentation consisting of very small, irregu- 

 larly toothed transverse ridges. The length of the ridges 

 hardly reaches a sixth of the diameter of the seta. They are 

 placed in a somewhat irregular system of two crossing spirals. 

 These sexual sette have been overlooked by Beddard, but they 

 give to us the best distinguishing character of this species. 



Remarks. — M. colletti Bedd. is nearly allied to two 

 species from Natal — M. gracilis Mich, and M. ivari Mich. 

 We might perhaps be justified in uniting these three species 

 into one, M. colletti Bedd., and to consider the examples 

 from Natal as varieties of Beddard's Zululand species, which 

 has the priority. But with the material at hand I think it 

 best to keep them sepai'ated provisionally. 



Microchgetus gracilis Mich. 



Microchaetus gracilis Michaelsen, " Oligochseten von Natal und dem 

 Zululand," Arkiv. ZooL, iv, nr. 4, p. 8. 1907. 



Hab. — Van Reenen's Kloof, Natal (teste Michaelsen). 



