194 
GREAT AND LITTLE BOGDO. 
inclined to the west, thus showing a transverse line of fault ; the gypseous mass 
occupying a symmetrical depression. 
The greater Bogdo presents analogous phenomena of succession, but on a larger 
scale. Being the highest point in all this region, and also remarkable for its pecu- 
liar vegetation and living animals, it has attracted both the superstitious worship 
of the nomadic tribes who live around it, and the special attention of every scien- 
tific traveller w T ho has approached it, including Falk, Pallas, Gbbel and Evers- 
mann. Modern geologists, however, are chiefly acquainted with it through a few of 
its fossil remains. Pallas, who visited it three times, describes the succession of 
the beds and their neighbourhood, with an exactness which we cannot too much 
admire in the * De Saussure of Russia,’ and he cites a remarkable Ammonite which 
has recently been described by M. Von Buch. The resemblance of this fossil to a 
characteristic Ammonite of the Muschelkalk, seemed to the latter author to indi- 
cate the existence of that formation in Russia. 
Professor Eichwald (who has not visited the spot) has recently published a short 
memoir, in which, in addition to an extract from Pallas, he gives the description 
of a true Orthoceratite supposed to have been collected at Bogdo by M. Gobel, a 
fact to which Colonel Helmersen had previously alluded. As the very circum- 
stantial and minutely detailed voyage of Gobel makes no allusion to the finding 
of any such body, and as the collection on which Professor Eichwald has formed 
his conclusions was sent from Dorpat, we cannot but think that one of the true 
Silurian Orthocerata of Esthonia, so abundant in the collection at that university 
(see p. 33), has been transmitted to the Professor at St. Petersburgh through mis- 
take or inadvertence. We searched most carefully for fossils on the spot, and the 
result of our labour was the acquirement of about twelve specimens of the Ammonites 
Bogdoanus and other shells, none of which resemble in the least the Orthoceras 
described by Eichwald. In describing the matrix or rock in which his Orthoceras 
is imbedded, that author mentions the existence of green grains, which is to us a 
convincing proof, that he had simply before him a portion of the chloritic Silurian 
limestone of Esthonia ; for we can positively assert, that the limestone of Mount 
Bogdo contains no such matter. Hence we presume, that the common Orthoceratites 
vaginatus of the Silurian limestone of Esthonia was not found at Bogdo, and con- 
sequently that Professor Eichwald’s conclusion, that this mount is of Silurian age, 
is without foundation. With all respect for his authority, we are also bound to 
