330 Scientific Intelligence. 



phylogenies and a final classification of these organisms can be 

 bnilt. c. s. 



2. Occurrence of Mastodon humboldtii in Northern Mexico. — 

 A small collection of Mastodon material, from near the line of 

 the Chihuahua al Pacifico R. R., was presented to the Yale Uni- 

 versity Museum in 1902, by Mr. Charles Sheldon (Yale 1890). 

 The remains include part of an upper tusk and fragments of a 

 tooth from Guerrero, near Concepcion, in the state of Chihuahua, 

 Mexico ; also the head of a femur, which was found about sixty 

 miles from Chihuahua. The tooth may be identified with the 

 third upper molar of Mastodon humboldtii Cuv., as the cross- 

 crests show the peculiar "double-trefoil" pattern characteristic 

 of that species, and otherwise agree closely with Prof. Cope's 

 definition of Mastodon ( = Dibelodon) humboldtii (Fourth Annual 

 Report, Geol. Surv. Texas). This identification is of considerable 

 interest, inasmuch as Prof. Cope stated (loc. cit.) that the sup- 

 posed occurrence of the species in Mexico was based on a misap- 

 prehension, the specimen Irom Mexico described as M. humboldtii 

 by Von Meyer (Palaeontographica, 1867) being subsequently 

 arranged by Cope under the new species Dibelodon tropicus. 



G. F. EATON. 



3. Petrography and Geology of the Igneous Rocks of the 

 Highioood Mts., Montana • by L. V. Piksson. Bull. 237, IT. S. 

 Geol. Surv., 1905, 208 pp., 7 pis. — The Highwood Mountains 

 form a group of much eroded volcanoes situated on the great 

 plains of Montana within the great bend on the Missouri River. 

 They present stocks of granular rocks filling the old conduits, 

 which are surrounded by a vast network of radial dikes. There 

 are some intruded sheets and masses of extrusive flows, breccias 

 and tuffs, remnants of the former cones. On the southeast there 

 is an interesting region of intruded laccoliths which affords exam- 

 ples of rock differentiation in place. 



The igneous rocks composing these varied masses are of alkalic 

 types, mostly basic in character with a prevailing dominance of 

 potash in the alkalies. They afford a number of interesting and 

 novel kinds, some of which, such as shonkinite and missourite, 

 have been previously described by the author in conjunction with 

 Mr. W. H. Weed. In this bulletin the geology of all these occur- 

 rences is described and the petrography of the different rocks given 

 in full detail with chemical analyses. The new quantitative system 

 of classification is used, giving an opportunity of testing its practi- 

 cal working. In conclusion, the bearing of the facts observed 

 on the origin and differentiation of igneous rocks is treated. 



4. Red Beryl from Utah; by W. F. Hillebrand. (Com- 

 municated.) — From Mr. Maynard Bixby of Salt Lake City, there 

 have recently been received three crystals of beryl which because 

 of their color — a rich raspberry-red — seem to merit notice. The 

 specimens show single crystals of short prismatic or tabular 

 shape, 3 millimeters in height and up to 7 millimeters across the 

 basal plane, implanted on imperfect topaz crystals. According to 

 Mr. W. T. Schaller, the only other forms are those of prisms of 



