Notices of Memoirs — Short Notices. 465 



3. EucEBATHERimi. — This is a singular quaternary ungulate found 

 hy W. J. Sinclair and E. L. Furlong in the caves of the Shasta 

 ■country, California. Its affinities are not clear. It may be placed 

 in the Ovinse, but cannot be regarded as intimately related to any 

 existing North American member of that group. The cranium is 

 larger than in the big-horn sheep, while the horn-cores are smaller, 

 are situated much further behind the orbits, and differ greatly in 

 form and curvature. Although there is a resemblance to Ovibos 

 in dental structure, the horn-cores are of an entirely different type. 

 A relationship with the cattle is excluded by fundamental differences 

 in dental structure. It is separated from the goats by the presence of 

 a lachrymal pit. This character serves to distinguish Euceratherium 

 from Haplocerus, from which it differs also in greater size, in the 

 shape and position of the horn-cores, and in the exclusion of the 

 parietal from the cranial roof. The description and plates appear 

 in Bull. Geol. Univ. California Publications, iii, 1904. 



4. Geology under the Planetbsimal Hypothesis of Eaeth- 

 Origin.— In the Bull. Geol. Soc. Amer. (xv, 1904) H. L. Fairchild 

 discusses the bearings on several problems in geology of the new 

 hypothesis of earth-origin recently formulated by T. C. Chamberlin. 

 This hypothesis will shortly be printed in full in a new text-book 

 by T. C. Chamberlin and E. D. Salisbury. Its comparison with 

 the nebular theory is thus given by Fairchild : " The old hypothesis 

 assumes the existence of a mass of incandescent vapour, with or 

 without a nucleus, which by condensation and rotation was 

 differentiated into successive rings, the latter being eventually 

 gathered into the planets while still retaining intense heat. From 

 this postulate there necessarily follows the conception of a cooling 

 earth, and hypogeic geology has been founded on the idea of crustal 

 solidification on a molten globe. The new hypothesis holds that 

 the disseminated planet-forming matter had lost its heat while yet 

 existing in the loose form, as rings or wisps of the parent nebula, 

 and that the globular planets were formed by the slow accretion 

 or infalling of cold discrete bodies or particles ('planetesimals '). 



" The old hypothesis assumes an originally hot globe with 

 shrinking on account of cooling. The new regards the globe as 

 originally and always cold at the surface, and the interior heat 

 as the product of gravitational condensation. The old view requires 

 continuous cooling of the globe, while the new allows the conception 

 of increasing internal heat. The old hypothesis makes the earth 

 of largest size at birth and of constantly diminishing volume. The 

 new regards the earth as beginning with a small nucleus and slowly 

 growing by surface accretion, but with large reduction of volume 

 by compression during and subsequent to the accretionary process. 

 The old hypothesis involves the recognition of a primal heated 

 atmosphere and ocean consisting of the more volatile substances 

 of the earth's mass. The new derives the present fluid envelopes 

 from the earth's interior by a slow process of expulsion due to 

 pressure and heat." 



Having thus distinguished the new theory from the old, Fairchild 



