34 AMERICAN JOURNAL 



The occurrence of the Greenland Limncea is exceedingly local, 

 thus a species was found by Mb'ller in a little hole between the 

 mountains opposite to the colonial buildings of Godthaab and 

 not a single specimen in any of the numerous other tanks, large 

 or small, which are found in a continuous row of nearly one 

 mile. Mb'ller tells that he took (July 30, 1840,) the wormen- 

 boat over to the clay bank of Kuksuk, and, after much searching, 

 at length found a tank with Limncea and Pisidium ; but only 

 single specimens were obtained, as they mostly walked on the bot- 

 tom so far out that it was not possible to reach them.* 



J. Vahl, Pingel, Holboll, Jorgensen, Mb'ller, &c, may have 

 collected, in the years 1829-45, over a thousand specimens, but 

 most of one variety. 



7. Limnjba (Limnophysa) Vahlii, Beck. Plate 4, figs. 1 — 5. 



T. obtecte perforata, pallide brunnea, pellucida lineis acicu- 

 latis spiralibus, interstitiis sgepe cancellatis strigse incrementi 

 castaneo albomarginato 2 vel 3 ; spira aperturam superans, colu- 

 mella strictiuscula torta, crassiuscula. 



Long. 22 mm., lat 9 m., apert. long. 11 mm. 



Animal grayish-green with minute yellow-white dots. (Moll.) 

 L. Vahlii, Moll., Ind. p. 2. 

 S. expansa, Haldem., Mgr. t. 9, f. 8, non absimilis. 



Brought from a tank at Amaraglik. (Moller.) 

 L. leucostoma. 



T. extus straminea, paries aperturalis et faucibus candidis. 



Long. 20 m., long, apert. 10J m. 



L. Vahlii, /?. leucostoma, Morch, Prod. p. 4. No. 11 /?. 



L. catascopium, Say, Haldem., Mgr. t. 1, f. 4, simillima. 



L. Molleri, Beck, Ntf. Vers. Kiel. p. 123, No. 4. 

 " Gerstf., Land u. Sussw. Conch, p. 37. 

 Probably from Tunnundliarbik. (Vahl., Holb.) 

 This variety is somewhat smaller and broader than the type, 



but differs chiefly by a thick layer of milk-white chalk, which 



covers all the inside and columella, giving the exterior of the 



shell a light straw color. 



ft. minor.' 



Spira longitudinis aperturse. 

 Long. 18 m., apert long. 11 m. 



* Holboll found Limncea sitting on stones, even when the water was 

 covered by ice lg- inches thick. 



