1909.] H. B. Preston : Aquatic animals from Tibet. 115 



REPORT ON A SMALL COLLECTION OF FRESHWATER 



MOLLUSCA {LI MALE A AND PISIDIUM) 



FROM TIBET. 



By H. B. Preston, F.Z.S. 



The Mollusca dealt with in the present paper were recently 

 collected b}^ Captain F. H. Stewart of the Indian Medical Service 

 at high altitudes in Tibet, and were placed in my hands for identi- 

 fication by Dr. N. Annandale, Superintendent of the Indian 

 Museum, Calcutta. 



Though there are a good number of specimens, only three 

 species appear to be represented, all belonging to the genera 

 Linmcea and Pisidium, and I would take this opportunity of ten- 

 dering m}' thanks to the Rev. E. W. Bowell and Mr. B. B. 

 Woodward, who have kindly assisted me in working at these 

 difficult groups. 



Limncea hookeri, Reeve. 



From the following localities : Gyantse, 13,120 feet, in a 

 pond which dries up in winter, two lots, adult and young; Mang- 

 tsa, 14,500 feet, in a stream from a warm spring which only freezes 

 during the coldest months (February and March ; during the rest of 

 the winter there is only a little ice at the edge), two lots, adult and 

 young ; Se-chen, 13,100 feet, in marshy pools, a number of speci- 

 mens, mostly adult ; — large quantities of spawn were observed under 

 stones in this locality. 



Though the shells vary somewhat in size and form, I am 

 quite able with the series before me to link them all up inte the 

 present species. 



With regard to the soft parts : Mr. Bowell reports that the 

 genitalia are very similar to those of the common European form 

 L. auricularia, Lin. The vas deferens is, however, markedly 

 shorter, and the radula is remarkable for the length of the cusps 

 and their subulate appearance, and also for there being no great 

 distinction in type between the laterals and marginals. 



Limncea bowelli, sp. no v. 



Shell rimate, acuminately ovate, rather solid, polished, shin- 

 ing, pale yellowish horn colour ; whorls 4, shouldered above, 



marked with rather coarse lines of growth ; 

 sutures deeply impressed ; columella de- 

 scending obliquely and dift'used above into a 

 thick callus which joins the upper margin 

 of the peristome ; peristome simple ; aper- 

 ture ovately, inversely auriform. 



Altitude 8-5 mm. 



>■ — ; — t — I — i — j—i Diam., major .. .. 5*25 ,, 



Vio. I. -Limn^abou'elii, Aperture, alt 5 „ 



Preston. ,, diam. .. .. 375 ,, 



