406 The American Geologist. June, isas 
guished from the genealogical records of the individual. It would seem, 
however, that just as the co-existence of a large number of individuals 
tends to perpetuate specific variation, so the simultaneous occurrence 
of abundance of species in one horizon and area is productive of the di- 
vergence of genera. 
We cannot enter further into details; enough has been written to show 
beyond contradiction the value and interest of this "Introduction to the 
Study of the Genera of Paleozoic Brachiopoda," with its concise de- 
scriptions of genera and passage-forms, their inter-relations, and affili- 
ated species. It is rendered complete by excellent specific bibliograph- 
ies, well considered genealogical trees, showing the common ancestry, 
diverging lines of descent, and affinities of genera, with their geological 
range, a register of genera and of species, authors, and general index. 
The work is most creditable to professor James Hall and his assistant, 
Mr. J. M. Clarke, and reflects honor on America in general and the 
state of New York in particular. It deserves to be carefully studied 
by invertebrate biologists in both hemispheres. We trust the publica- 
tion of the second part will be proceeded with, and that by its rapid 
completion, on similar lines of thought, science may be enriched by a 
general view of the evolution of the Brachiopoda. It is much to be de- 
sired that the relations of the Secondary and Tertiary species should be 
discussed in a like thorough, philosophical, and generally satisfactory 
manner. 
We have become so convinced of the advantages of this method of 
treatment, that we have begun to form the nucleus of a collection in the 
Brighton Museum, destined to illustrate the evolution of genera among 
the Brachiopoda.— Science. 
AN EXTINCT GLACIER OF THE SALMON RIVER 
RANGE. 
By Geo. H. Stone, Peyton, Colorado. 
West of Salmon City, Idaho, lie the Salmon River mountains. 
The}^ rise quite steeply from the adjoining vallej^s to an elevation 
of somewhat more than 8,000 feet above the sea. The range is 
ver}' snow}', being well exposed to the moist winds from the Pa- 
cific ocean. Its rocks consist of ver}- ancient quartzites, slates and 
schists, alternating with areas of coarse granites and a few extru- 
sions of rather recent acidic volcanic rocks. The main range 
trends nearly- north and south, and there are several spurs project- 
ing westward and northwestward. The masses of upheaval have 
been dissected into a multitude of valleys and cirques and show 
every sign of geological old age. 
