1889.] 



Western Hihialayas and Lelira Bun. 



113 



The clitollum ])reBents veutrally a very curious appearance owing 

 to the structures about to be described. Between somites XV and XVI, 

 and also between somites XVI and XVIT, there is a pair of oval depres- 

 sions in the middle of each of which stands a little papilla. Between 

 somites XIX and XX there are similar structures, but the depressions 

 are much less marked and the whole thing is smaller. These structures 

 are a very little further from the ventral median line than are the 

 ventral pair of sette on each side. The male pores are placed in somite 

 XVII a little further still from the median ventral lino ; they are on 

 papillas which lie in very deep pits. These structures are shewn in PI. 

 Ill, Pig. 1. 



The oviducal pores are placed anteriorly to the set© in somite XIV ; 

 they are sejoaratcd from one another. 



The spermathecal pores are very well marked slit-like apertures 

 placed between somites VII and VIII ; they lie nearer the middle 

 line than do setce 3.* The dorsal pores, intersomitally placed, are 

 visible behind the clitellum ; they are esioeoially well marked at the 

 posterior end of the body. 



Nephridiopores are not visible. There are eight setas in each 

 somite ; they are confined to the ventral surface of the body. Their 

 arrangement in eigl^t longitudinal rows is what chiefly strikes one on 

 examining a spirit specimen. In about the anterior two-thirds of the 

 body setfB 1 and 2, and 3 and 4, lie neai-er to one another than do sotee 2 

 and 3, that is to say, the setas are placed in couples, but this arrangement 

 gradually changes and in about the posterior third o£ the body the eight 

 setoe still lying in a row on the ventral surface are almost equidistant 

 from one another. The ventral gap remains however a trifle wider than 

 the interspace between any two seta?. 



The full complement of setre is present in the clitellum, but in 

 somite XVII setoe 1 and 2 are replaced by the groups of penial Setse 

 described below. 



Septa. — The most anterior septum is septum IV — V (i. e., the 

 septum which foi'ms the boundary between somite IV and somite V). 

 This and septum V — VI are very thick being exceedingly muscular. 

 The next septa which are developed are, I think, septa ¥111 — IX, IX — X, 

 and X — XI. Those are all fairly muscular and placed close togethoi', 

 that is to say, they do not correspond in position with the extei'nal 

 divisions between the somites. It is tliereforo exceedingly difiicult to 



* I adopt tlio couvoniont, systism of immbcrrag the sclic snggcate^cl by Bouluim, 

 seta 1 being tho sota which lies nearest the morlian ventral Hue on eifclier side ; seta 

 2 the sotn immediately beyond seta 1 and so on. 

 15 



