49 
2. On a new species of Lymnjea from Thibet. 
By Lovell Reeve, F.L.S., F.Z.S. etc. 
Lymncea Hookeri. hymn, testd ova- 
td, tenuiculd, conspicue umbilicatd, 
anfractibus quatuor ad quinque, con- 
vexis, superne depresso-rotundatis, 
suturis subimpressis, aperturd orbicu- 
lari-ovatd, marginibus lamind latius- 
culd subverticali conjunctis; sordide 
olivaceo-fused. 
The above-described freshwater mollusk, 
collected by Dr. Hooker on the Thibetian 
or north side of Sikkim Himalaya, at 18,000 
feet elevation, belongs to the same type as our well-known Lymncea 
peregra , and affords an interesting addition to the evidence which 
has been in part collected touching the wide geographical distribu¬ 
tion of corresponding forms of plants and animals over those parts of 
Europe and Asia where there are no extensive mountain-barriers. 
The European Lymncea stagnalis has been collected as far east as 
Affghanistan, and the typical form of Lymncea peregra is very cha¬ 
racteristic in this species from Thibet. A depression of the whorls 
next the sutures, which gives a more orbicular form to the aperture, 
and a conspicuous umbilicus, which is not in any degree covered by 
the columellar lamina, prove it to be specifically distinct from L. 
peregra ; and these characters do not appear in the various modifica¬ 
tions of that species arising out of its more or less ventricose growth, 
or more or less attenuated convolution. South of the Himalava 
«/ 
range, where Dr. Hooker reckons the snow-line to be 5000 feet 
lower than on the north side, and 3000 feet low T er than the locality 
inhabited by this species, the Lymncece are of quite a different type, 
more especially in the plains of Bengal, where the shell, owing to its 
being formed in so much warmer a temperature, is of stouter growth, 
and characterized by some design of colouring. The European types 
of Lymncea, ranging over Russia and Siberia, appear abundantly in 
the stagnant waters of North America; and some are identical in spe¬ 
cies. L. elodes of Say, inhabiting Pennsylvania, is doubtless the 
same species as the European L. palustris; L. truncatula of the 
same author appears to be identical with L. desidiosa; and the L. 
peregra, represented by L. Hookeri in Thibet, is represented in Penn¬ 
sylvania by Say’s L. catascopium. The Lymncece of Australia are of 
a remarkable and very distinct type from either of those mentioned 
above. 
I have much pleasure in naming this Thibetian Lymncea after the 
indefatigable traveller, whose researches into the natural and phy¬ 
sical history of that remote country into which few have penetrated, 
are likely to be attended with such important results. I have placed 
the specimens in the British Museum. 
The figure in outline is of the natural size. 
No. CCIY.— Proceedings of the Zoological Society. 
