igoS.] J. Stephenson : The Anatomy of some Aquatic Oligochceta. 275 



they are composed is perfectly clear^ like clear glass ; but the majority contain also 

 a quantity of granular matter, opaque, and of a dark brown colour, which may 

 be aggregated within the corpuscle into all kinds of irregular shapes (fig. 43). Some 

 corpuscles contain no granular matter and are quite clear. 



Alimentary tract. — The pharynx occupies the second, third, fourth and fifth 

 segments , it is lobulated in appearance (fig. 41), this being due to the large cells with 

 which it is surrounded. The cesophagus , in the sixth and seventh segments, has in its 

 walls a number of minute brownish globules , similar to those described in the aliment- 

 ary tract of the previous genera ; these globules are present throughout the subsequent 

 length of the tract. The stomach is shown in fig. 41 as a globular dilatation in the 

 eighth segment ; it varies, however, in distinctness, it may be but a slight dilatation, 

 or there may be no recognizable stomach at all. Since the actual character of the 

 walls of the tract is the same from the œsophagus onwards, it follows that in the 

 last case no differentiation of separate parts of the canal exists behind the pharynx. 



The intestine presents the same phenomena of a reversed ciliary action and 

 antiperistalsis as have been noted for Nais and Pristina. 



It will not be necessary to describe the remaining systems in detail. The 

 pharyngeal commissures of the vascular system form a plexus, not a series of simple 

 arches. The first nephridium is in the seventh segment ; on one occasion it was 

 seen in the sixth, and fig. 52 shows a specimen where it is drawn in what 

 appears to be the fifth segment. In the case where it was seen in the sixth, 

 the dorsal setae were observed to begin in the fifth segment ; and the figure just 

 referred to is {v. antea) that of an animal whose anterior end is not fully developed. 

 It would seem, therefore, that one, or in the second case two, segments are still to 

 be added before these particular animals are fully formed ; and we may here compare 

 what was said previously as to the possibility of early separation of the posterior . 

 animal, before the full number of anterior segments has been produced, being the 

 rule in Slavina. The two halves of which the cerebral ganglion of the Naididse 

 is always more or less obviously composed, are much more distinct in this species than 

 is usual. Figures 44 and 45 show it to consist of two oval or somewhat triangular 

 masses, distinct from each other, but closely apposed in the middle line. Reproductive 

 organs were not observed. 



Only two species of Slavina are described by Michaelsen [3], and of these only 

 5. appendiculata , Udek., possesses cutaneous papillae. This species has, besides small 

 papillae, regular circular rows of larger sensory projections, which correspond, I 

 think, to the papillae I have described for the present form. There can be little 

 doubt as to the close connection of this form with 5. appendiculata, from which latter, 

 however, it differs in possessing only one row of the large papillae per segment, in 

 having plexiform instead of simple commissural vascular arches, as well as, perhaps, 

 a smaller number of setae in the sixth dorsal bundle. I propose for it the name 

 Slavina punjahensis. 



