246 J. Stephenson : Tivo Oligochxte Worms. [Vol. I, 



General Remarks. 



The animal described above agrees in most points with the 

 definition of the genus Chcetooaster as given by Michaelsen. It 

 differs, however, in not possessing a greatly elongated third segment, 

 which is a characteristic of the genus as described by him ; for 

 though, as has been said, there is some difficulty in delimiting the 

 anterior segments, still the third appears to be defined by septa on 

 each side, and, as in C. punjabeiisis, to be practically commensurate 

 with the oesophagus ; and apart from this, whatever the exact 

 limits of the first six segments ma)^ be, there is hardly room for 

 an}^ one of them to be " greatly elongated " without cramping 

 some of the others almost out of existence. The receptacula 

 seminis of this genus are also said to be in the fifth segment, while 

 I have described them above as attached to the posterior face of 

 septum 5- ; I would not, however, lay too much stress on the con- 

 dition of the single, apparently not fully developed, specimen, 

 in which these organs were found. 



On the other hand, the resemblances between this form and 

 the various species of the genus Chcetogaster are many and evident ; 

 such, especially, are the absence of the dorsal and the arrangement 

 of the ventral setae, the single pair of lateral transverse blood- 

 vessels, and the separation longitudinally of the anterior part of 

 the ventral nerve-cord into two. It will be better, therefore, for 

 the present to place this form in the genus Chcetogaster , as was done 

 with C. punjabensis, and as Annandale has done with the allied 

 species recently described by him ; and I propose the specific 

 name pellucidus for it. 



Besides the presence of the cuticular prominences on the head, 

 the distribution of the nephridia, the details of the asexual mode 

 of reproduction, and the co-existence of asexual with sexual repro- 

 duction, a few further points of interest present themselves for 

 remark. 



With regard to the granular matter contained in the cerebral 

 ganglion, it is interesting to recall the crescentic refractile particle 

 in C. punjahensis, the sense-organ (? otocyst) in the cerebral gang- 

 lion of C. hengalensis (Annandale, Journ. Asiat. Soc. Beng.^ New 

 Ser., vol. i. No. 4, 1905, p. 117), and the definite otocyst (a relatively 

 large, globular, transparent cyst) of C. spongillcs (ib. id., vol. ii, 

 No, 5, 1906, p. 188). With this may perhaps be brought into 

 connection the condition in C. diastyophus (Gruith.), a European 

 species, in the definition of which Michaelsen says, " gehirn mit 

 medianer Chitin (?)-Platte am Hinterrande." It seems possible that 

 we have here a series of degenerative changes, from the fully- 

 developed organ 01 C. spongillcs, through the doubtful otocyst of 

 C. bengalensis, to the apparently solid aggregate in the brain of 

 C. punjabensis and the chitin-like plate at the posterior part of the 

 brain of C. diastrophus [cf. the position in C punjabensis) ; finally 

 we have the dispersal in granular form of this so.id matter, as in 

 most specimens of C. pellucidus, ox its entire absence, as in other 



