Page:The Geologist, volume 5.djvu/134

110 tions ;"—viz. to land-slips, or dislocations of rocky masses by gravitation, operating upon shaken country.

All such are in directions on the surface tending towards transverse of shock.

2. Earthquake shocks traverse furthest and most powerfully in the axial lines of mountain chains, and vice versa, by reason of the fact that in the former lines the rocky masses are most solid and homogeneous.

3. Every earthquake emanates from a centre, which, is practically a point or line, or small area or surface; and the waves of pulse, necessarily, are propagated in all directions outwards from such centre of impulse, therefore in opposite directions.

We should suggest to our correspondent to study Mr. R. Mallet's papers on, 1. "The Dynamics of Earthquakes," Trans. Roy. Irish Acad. 2. The article "Earthquake Observations," by the same author, in the 'Admiralty Manual,' 3. Mr. Mallet's first and subsequent reports on "The Facts of Earthquakes," Trans. Brit. Association.

were felt at Cosenza (Calabria Citerior) on the 14th October, and at Ravenna on the 16th October last. On the 29th, a waterspout passed over Rome, causing much damage; the day after there occurred a violent tempest, and the magnetic instruments were greatly agitated. M. Alexis Perrey, Professor at Dijon, who for many years has furnished an annual statement of the shocks experienced by our globe, has sent to the Royal Academy of Belgium, a new "Note sur les tremblements de terre en 1859."

.—A caudal vertebra of Plesiosaurus Chilensis has been transmitted to me for identification by W. Bollaert, Esq., F.R.G.S., from San Vicente, near Talcahuano, in the neighbourhood of Concepcion, Chile. This species was founded by Gay (Historia fisica y politica de Chile), on various vertebral bones, which were found at the small island of Quiriquina, off Cape Talcahuano, in the Bay of Concepcion. The vertebra from San Vicente appears to present no specific difference from the Plesiosaurus Chilensis of Gay. A fragment of paddle-bone was found in the same locality.—.

.—Professor Agassiz, in a letter to Dr. Silliman, describes some new Sauroid remains of very great interest, discovered by Mr. O. C. Marsh, a student of Yale College, from the coal-formation of South Joggins. These are two vertebræ, which have excited Professor Agassiz's interest in the highest degree. He says, "I have never seen in the body of a vertebra such characters combined as are here exhibited. At first sight they might be mistaken for ordinary Ichthyosaurus vertebræ; but a closer examination soon shows a singular notch in the body of the vertebra itself, such as I have never seen in reptiles, though the character is common in fishes; we have here undoubtedly a nearer approximation to a synthesis between fish and reptile than has yet been seen. . . . The discovery of the Ichthyosauri was not more important than that of these vertebræ; but what would be the knowledge of their existence without the extensive comparisons to which it has led? Now these vertebræ ought to be carefully compared with the vetebræ of bony fishes, with those of sauroid fishes, of selachians, of batrachians, of the oolitic crocodilians, of the newer crocodilians, of the ichthyosaurians, and of the plesiosaurians, and all their points of resemblance, and difference stated; because I do not believe there is a vertebra known thus far, in which are combined features of so many vertebræ in which these features appear separately as characteristic of their type."