338 MB. r. E. BEDJJABD OK EAKTHWOE,Mf< [Apr. 16, 



P. JciUndiiicnsis\ The appearance is very characteristic of those 

 species, and, apparently, of those only. The grooves between the 

 several' segments are perfectly distinct. The appearance of this 

 " Pubertatspolster " is indistinct in the figure (text-fig, 83). 1 

 could not find a similar structure in Poh/toreutus fnni, between 

 which and P. Mindinensis the present species seems to stand. 



The seUe have the usual arrangement which characterizes the 

 genus, i. e. the two seta3 of the ventral couples f^tand apart, while 

 those of the lateral couples are closely paired. 



As is the case Avilh some but not all of the species of this genus, 

 the ;prostoynium does not in the least impinge upon the buccal seg- 

 ment, but is sharply marked off from it by a transverse groove ; 

 the prostomium is in fact what Michaelsen has called " prolobisch." 

 There are of course no dorsal pores. The nepliridiopores are in 

 front of the lateral couples of setae. 



Such are the principal external characters of the present species, 

 which are, T think, sufficient of themselves to establish_ its dis- 

 tinctness. In internal characters the members of this genus 

 mainly differ in the form of the spermathecal sacs and of the 

 spermiducal glands. The other viscera are not so variable, unless, 

 indeed, the form of the sperm-sacs in different species is really 

 distinctive of them and not merely due to varying stages of de- 

 velopment. I am disposed to think, from my observations upon 

 the present species, that the sperm-sacs do offer characters of some 

 use in discriminating the species of Pohjtoreutus from each other. 



In describing Pohjtoreutus Jinni '^ I drew attention to the extra- 

 ordinary slenderness of the sperm-sacs, which extend like white 

 threads, hardly, if at all, thicker than the sperm-ducts, for some 

 distance backwards. Michaelsen has by a query suggested that 

 this appearance may be due to immaturity — and a reasonable 

 enough suggestion. And yet I am not altogether disposed to 

 agree with him, since in Polytoreutus hindei I find precisely the 

 same state of affairs. The two sperm-sacs are slender threads 

 which reach back to about the level of the commencement of the 

 spermiducal glands and are swollen here and there like a ganglio- 

 nated nerve-cord. Now the present specimen is fully mature, as 

 was that of Pohjtoreutus finni, upon which I founded that species. 

 The probabihties appear to me to be in favour of considering the 

 condition of the sperm-sacs as characteristic of the species and not 

 to be due to immaturity. However, the question cannot be settled 

 definitely at present The sperm- duct is very noticeable in the 

 dissection on account of this thickness, which is fully that of the 

 duct leading from the spermathecal sac to the egg-sac. It has a 

 swollen sac at its beginning, as in the other species of the genus. 



The two spermiducal glands are white thick tubes of some length ; 

 they have not the extraordinary thinness and length that character- 

 izes those organs in Polytoreutus finni. Each gland was somewhat 

 bent like an elbow, a feature often shown by these glands in 



^ See Becldard, P.Z. S. 1901, vol. i. test-fig. 50, p. 188, and test-fig. .51, p. 190. 

 ^ " A Contribution to our Knowledge of tlie Oligochffita of Tropical Eastern 

 Africa," Quart. Journ. Micr. Sci. xxxvi. p. 241. 



