48 THE POPULAR SCIENCE MONTHLY. 



servations in the Rocky Mountains do not tally well with D'Orbigny's 

 notes from the Andes, since out of 156 species discovered in South 

 America, he found only 13 between the thirty-fourth and forty-fifth 

 parallels of latitude which corresponds to the district of north lati- 

 tude considered here and only 10 species were found above 5,000 

 feet. My list of the Rocky Mountain mollusca, on the contrary, shows 

 that 55 species out of the 138 inhabit heights exceeding 5,000 feet, 

 and 10 species have been found above 10,000 feet. These latter, 

 however, are all recorded from mountains south of the thirty-ninth 

 parallel; but it is safe to say that, where there is moisture, a goodly 

 collection of mollusks can be made in the mountains of the Terri- 

 tories all the way up to the timber-line. This is probably true of all 

 parts of the world. 



In a recent paper on the hypsometric distribution of mollusca in 

 Europe, communicated to the French Academy of Sciences at Paris, 

 at their meeting on October 11, 1875, M. P. Fischer alludes to the 

 great regularity with which plants thrive on mountains, each at a 

 certain height. The terrestrial mollusca, being unprovided with means 

 of locomotion enjoyed by birds and insects, and being, moreover, 

 dependent upon vegetable life for food, could not fail to be discovered 

 in the same way as plants, and this supposition he confirmed by ob- 

 servation. Each species extends to an altitude the limits of which it 

 does not overstep. M. Fischer has verified this in the central Pyrenees 

 as well as in the Alps, and divided the altitudes into five zones, com- 

 prised between 1,500 feet and 7,500 feet. Each zone is distinguished 

 by the name of a species of Helix. Thus, in the Pyrenees, the first 

 zone, ending at a height of 3,000 feet, is called that of Helix carthu- 

 siana ; the second, ending at 3,600 feet, Helix aspersa ; the third, 

 terminating at 4,500 feet, Helix limbata ; the fourth, limited at 6,000 

 feet, Helix nemoralis ; and the fifth, ending at 7,500 feet, Helix caras- 

 filensis. In the Alps, at the same altitudes, the names of the zones 

 are respectively Helix carthusia?ia, obvoluta, Fontenelli, sylvatica, and 

 glacialis. A few individual mollusks will, indeed, climb as high as 

 9,000 feet, but they all stop at the limit of perpetual snow. Various 

 genera of fluviatile mollusks do not ascend higher than 3,000 feet, a 

 circumstance which the author considered of some importance to 

 geologists, since it proves that in the quaternary beds the fossiliferous 

 Btrata containing those genera, such as Neritina, Paludina, etc., were 

 deposited at small altitudes. The Lake of Goube, about three hours' 

 walk from Cauterets, 5,364 feet above the level of the sea, is thickly 

 peopled with trout, frogs, and mollusks. 



The results of this inquiry into the geographical distribution of 

 mollusks in the mountainous West are meagre enough, but may be of 

 some use in future investigations. Whether this central region is a 

 true zoological province considered with reference to the mollusca, 

 and what is the origin of its fauna, are hardly to be answered yet. 



