rgog.] J. Stephenson : Aquatic animals frojii Tibet. 107 



2 — 5 mm. This can hardly, I think, be accounted a specific differ- 

 ence. I have recently [ Mem. Ind. Mus., i, No. 36, p. 277, pi, 

 XX (1908) ] given a description of an .Eolosoma from Lahore, identi- 

 fying it as .E. hemprichi, which is about the dimensions of these 

 specimens from Tibet, and which is therefore also considerably 

 smaller than .E. Iiemprichi according to the figures given above. 



ChcBtogaster orientalis, nom. nov, 



1907. ChcBtogaster pellucidus^ Stephenson, Rcc. Ind. Mus., vol. 

 i, p. 237 (1907). 



No. 42, Se-chen, Tibet ; 13,100 ft. ; 22-iv-07. 



Three specimens without sexual organs, and one frag- 

 ment, together with the specimen of Nais sp. 

 No. 49. Gyantse, Tibet ; 13,120 ft. ; 26-vi-07. 



Two specimens without sexual organs ; dark brown in 

 colour, probably due to mode of fixation. 

 No. 'i^. Gyantse, Tibet ; 13,120 ft. ; 20-viii-07. 



Two specimens without sexual organs, with several frag- 

 ments consisting of detached buds. 



The specimens probably consisted originally of complete 

 chains of four or five individuals, which broke up at the moment of 

 killing and fixing. They correspond closely with the species des- 

 cribed by me as C. pellucidus from Lahore. Since writing that 

 account (referred to above), however, I have, through the kind- 

 ness of Dr. Walton, of Kenyon College, Gambier, Ohio, tr.S.A., 

 received a copy of his paper "The Naididse of Cedar Point, Ohio," 

 1906 {American Naturalist, vol. xl, No. 478) ; he there describes 

 as C. pellucidus a species found by him ; and since the name 

 belongs by priority to that form, I have chosen orientalis for the 

 species now under discussion. 



I was at first inclined to see a difference between the present 

 specimens and the form previously described by me in the relative 

 length and thickness of the pharyngeal region as compared with 

 the posterior part of the bod5^ I find, however, that in the 

 processes of fixation, etc., the phar^mgeal region contracts both 

 in length and breadth, while the body in the "crop" region 

 appears to become broader than in life : in specimens from Lahore 

 so treated the result is a close approximation to the condition in 

 which the Tibet specimens were found, e.g. : — 



Length of pharyngeal Length of Ijody 



Lahore form 

 Tibet No. 83 

 Tibet No. 49 

 Tibet No. 42 



region. 



posterior to pharynx. 



•25 mm. 71 mm. 



•29 .. 75 ,, 



•088 ,, "24 ,, 



•II '> \ -35 ,, 



