376 Reviews — Silurian Crinoids of Chicago. 



noticed by Abich, break through and alter Jurassic sediments. 

 Some of them are hypersthene-augite andesites (the former mineral 

 dominating markedly in two specimens) — that on the summit distin- 

 guished by the epithet vitrophyrischer — and another is a hornblende- 

 biotite-dacite. These accordingly seem to be nearly related to the 

 volcanic rocks of Elbruz and Kasbek, and to belong to the same 

 group as those of Ararat. 



We have dwelt chiefly on the petrology, because that has received 

 such close attention, but valuable geological information is intro- 

 duced into the narrative throughout the book. Herr Merzbacher, 

 however, does not forget to notice the physical geography, the 

 natural history, the inhabitants of the various districts, their dress, 

 accoutrements, architecture, and habits of life. All these are 

 abundantly illustrated by reproductions of photographs, which are 

 valuable to the ethnologist, and will be more so in the future, as the 

 distinctive characteristics of tribes once isolated by the obstacles of 

 a mountain region disappear before the advance of European 

 civilization. The book, in fact, is a monument of laborious research 

 and a perfect mine of information, which will be useful alike to the 

 mountaineer, the traveller, and the scientific student. 



T. G. BoNNE-sr. 



II. — Silurian Ckinoids of Chicago. 



The Paleontology of the Niagaran Limestone in the Chicago 

 Area. The Crinoidea. By Stuart Weller. Bull. Nat. Hist. 

 Survey Chicago, IV, part 1, 153 pp., xv pis., and text-figures ; 

 27 June, 1900. 



THE Crinoids of the Niagara Limestone of the Chicago region, 

 including south-eastern Wisconsin, have been the subject of 

 publications by Winchell & Marcy, James Hall, and S. A. Miller. 

 Nevertheless the amount written was by no means proportional to 

 the size of the fauna, and a large number of species escaped notice 

 even in Wachsmuth & Springer's great Monograph of the North 

 American Camerata. This has not been due to want of material, 

 for the collections of these fossils are many and rich, but to their 

 unattractive appearance as, for the most part, internal casts of the 

 theca alone in a coarse dolomite. Gratitude and praise are therefore 

 due to the energetic instructor in palaeontology at the University of 

 Chicago, Dr. Stuart Weller, for the trouble that he has taken in 

 deciphering this unpromising material and for presenting the 

 results in this clearly written and clearly illustrated memoir. 



The results are of wider interest than might have been anticipated. 

 It was hardly to be expected that Dr. Weller should discover new 

 facts of morphology, nor has he done so. But the Crinoidea, perhaps 

 to a larger extent than the other elements of the fauna, shed much 

 light on the problems of distribution. They are represented by no 

 less than 69 species (Dr. Weller says 68), classified as follows : — 

 MoNOCYOLicA, Inadunata, Stephanocrinus 1 sp., Myelodactylus 1 sp., 

 Zophocrinus 1 sp. ; Adunata, Platycrinus ? [probably one of the 



