191S.] T. Stkptteistson : Olif/ochnefa of the JnU Tjole. 11 



around the opening of the oesophagus into the crop ; these are part of 

 the lining epithehum, as is seen in longitudinal sections, where they 

 appear as prominent cells projecting into the lumen, almost constituting 

 a circular valve. 



There is a considerable granular more opaque mass in the cerebral 

 ganglion, as in some other species of the genus (c/. Stephenson, 6). 



Remarks. — The species is a well marked one, the large number of 

 setae being very characteristic. In addition, the practical equahty in 

 length and thickness of the terminal prongs of the setae, even to the 

 highest powers (correctly shown in Annandale's figure), with the short 

 but distinct oesophagus, will also serve as good marks of distinction. 



Not having noticed, in those species of Chaetogaster which occur in 

 the Punjab, any specially curved line of insertion of the setae, I was 

 much struck by this very marked feature in the present specimens ; the 

 curvature seemed to me to be even more accentuated than in Annandale's 

 figure. It is not, however, peculiar to this species ; Miss Davies, in 

 describing C. australis (3), which has resemblances to the present species, 

 mentions that the setae are arranged in the form of a semicircle, except 

 in the case of those of segment ii ; Mdlle. Dehorne mentions it in her 

 study of C. dia/phanus (4), and adds that this arrangement is even more 

 distinct in C. limnaei. 



I do not add to the hst of distinctive features of C. bengalensis the 

 presence of a posterior sucker (the anterior sucker of Annandale is the 

 margin of the mouth, as in the case of the leech). The posterior sucker 

 is mentioned by Annandale in his original account ; in C. australis, 

 Miss Davies says, " at the posterior end there is no definite sucker, but 

 the animal seems capable of sHghtly flattening its body so as to some- 

 what resemble one " ; and for C. victoriensis, " movement takes place by 

 means of a series of contractions and expansions with the aid of anterior 

 and posterior suckers, somewhat like a leech." I have not been able to 

 see the posterior sucker in the types of C. hemgalensis, nor in the present 

 batch of specimens ; in Annandale's figure it appears to be merely the 

 margin of the anus, — but this aperture is not provided with any special 

 musculature discoverable either in the examination of mounted specimens 

 or in longitudinal sections. Notwithstanding the more or less definite 

 statements I have quoted above, I do not think there will be found in 

 any species of Chaetogaster a posterior sucker, that is, a definite muscular 

 organ, whether including the anus or not. I believe that the attachment 

 of the animal at the posterior end takes place by means of the hinder 

 setal bundles, the hooked ends being turned forwards and taking hold 

 of the substratum (as in the case of backward progression, c/. Stephenson, 

 6, p. 237) and that Mdlle. Dehorne (on C. dia/phanus) correctly hkens the 

 mode of progression to that of a caterpillar,— " I'animal se deplace a 

 la fa9on des chenilles arpenteuses, les soies bucco-pharyngiennes jouant 

 le role de harpons, les soies moyennes et posterieures fixant la chaine au 

 substratum." 



If I might venture an additional word of criticism, it is that sections 

 do not show any special thickness of the pharyngeal wall ; nor is there 

 any peculiarity, as Annandale supposes, in the manner of insertion of the 

 setae of segment ii. 



