Dr. J. Neeggerath on the Origin of the Rock-salt Formation. 193 
near their origin, are three triangular acuminated scales, or 
cuticular processes. A large rounded warty excrescence is 
situated midway, on the inner and lower part of the foot. The 
specimen was a male. ‘The tail nearly three quarters the 
length of the body, very small, or strangulated at its insertion, 
becoming abruptly very large, and gradually tapering towards 
the extremity. ‘The caudal vertebrae were not distinguishable 
through the mass of fat with which they were enveloped, and 
of which the tail was principally composed. There were no 
transverse folds or ridges on the tail, its‘surface being perfectly 
uniform, nor were the hairs disposed in distinct whorls. The 
tail of this species therefore differs essentially from that of the 
eristata, as described by authors, and induces us to wish that 
Desmarest had changed the name of the genus for some one 
more expressive of the species which compose it. 
Length of the male Condylura prasinata, from the end of 
the snout to the origin of the tail, four and a half inches. 
Length of the tail three inches. Circumference of the body 
three inches and three quarters. Circumference of the tail, 
at the largest part, one and a halfinch. Average length of 
the nasal radii five-twentieths of an inch. Length of the hand 
eight-tenths of an inch. Length of the longest nail three- 
tenths of aninch. Length of the foot one-inch and one-tenth. 
Length of the longest nail of the foot five-twentieths of an inch. 
Distance between the eyes rather over three-tenths of an inch. 
From the end of the snout to the eyes seven-tenths of an inch. 
Milton, May 4, 1825. 
XXIX. On the Volcanic Origin of the Rock-salt Formation. 
By Dr. J. NecGERATH*. 
I HAVE read with pleasure M. de Charpentier’s letter of 
the 22d of March 1825, to M. L. de Buch, with the valu- 
able remarks of the latter meritorious naturalist attached to 
it, which have appeared in Poggendorf’s Annalen der Phys. 
und Chemie 1825, St. 1. 
It describes a great vein at Bex in Switzerland, which i 
between perpendicular strata of anhydrite, and rises from 
80 to 40 feet, with fragments of anhydrite: this vein is filled 
with silicate of lime, and a considerable quantity of sand and 
dust of anhydrite, which are collectively combined together 
into a firm mass by a pure rock-salt, perfectly free from 
water: this mass is covered with a powder and has no cavities 
with crystals. All this indisputably evinces, that it is a fissure 
* From Schweigger’s Journal, N.S. Band xiv. p. 278. 
Vol. 67. No. 335. March 1826. 2B produced 
