B. Hobson—WMexican Volcanoes. 5 
Series. It is quite possible, however, that this species may occur in 
both the lower and upper beds of the Lower Carboniferous. 
The specimens! discussed here have been presented to the Sedgwick 
Museum by Mr. Price, who informs me that he hopes to make yet 
further collections from the Chepstow beds. Such should prove to be 
of considerable interest if well-preserved impressions can be obtained. 
II7.—Awn Excursion to THE VotcanorEs oF Neryapo DE ToLuca AND 
JoruLto In Mexico.” 
By Bernarp Hoxson, M.Sc., F.G.S., 
Lecturer in Petrology and Geology in the Victoria University of Manchester. 
(PLATE II.) 
N connection with the meeting of the Tenth International Geological 
Congress in the city of Mexico, an excursion, known as the Jorullo 
Excursion, was organised, of which the following is an account :— 
Nevado de Toluca. 
Under the leadership of Mr. T. Flores, geologist of the Mexican 
Geological Institute, a party of thirty geologists left Mexico city 
(altitude 7,432 feet) on August 20th for Toluca (altitude 8,761 feet), 
distant 46 miles by the Mexican National Railway. From a small 
hill close to Toluca an excellent view of the town itself and the 
extinct volcano of Xinantecatl or Nevado de Toluca (altitude, 
according to Flores, 14,973 feet), distant about 123 miles to the 
south-west, is obtained. It lies at the southern edge of the great 
Mexican plateau (Mesa central), and has the form of an abruptly 
truncated cone, resembling that of Vesuvius before the eruption which 
destroyed Pompeii and Herculaneum. On August 21st we left Toluca 
by train for Calimaya, 11 miles distant and on the east side of the 
volcano. At Calimaya station we were met by a body of rwrales or 
rural mounted police, armed with carbines, swords, and revolvers, who 
were to form our escort. They were holding horses for our use. We 
mounted, and rode at first by a gently ascending road through fields of 
maize and agaves (American aloes). The road then followed the bank 
of a barranca or stream-gully, which was dry. We dismounted to 
examine the excellent section exposed. The walls of the barranca 
were composed of well-bedded white pumiceous tuff, the lapilli 
varying in size from that of peas to that of a fist or larger. In one 
place the tuff was seen to overlie a bluish-grey bed of volcanic sand, 
in another the underlying bed consisted of soft black peat-like soil, 
1 Carb. Plant Coll., Nos. 1478-1484. 
2 For most of the facts in this paper I am indebted to two papers, ‘‘ Le Xinantecatl 
ou Volcan Nevado de Toluca,”’ par T. Flores, and ‘‘ Le Jorullo,’’ par E. Ordonez, 
both forming part of the ‘‘ Guide des Excursions du X* Congrés Géologique 
International, Mexico, 1906.’’ An excellent general map of Mexico on which the 
route of the excursion can be followed is the ‘‘ Carte du Mexique. Dressée au dépot 
de la Guerre,’’ par Mr. Niox, scale 3553550 = 47°34 miles to 1 inch, date 1873, price 
1 franc plus postage, from H. Barrére, 21, Rue du Bac, Paris. Of railways it 
shows only one, but the railways up to date are shown on Rand, McNally, & Co.’s 
Indexed Atlas of the World, Map of Mexico, scale 72 miles to 1 inch. 
