Geology and Natural History. 87 



chief characteristics of the author. The ai^plication of the term 

 Epigene to include both aqueous and volcanic rocks, in contrast 

 to the plutonic igneous rocks to which Lyell ^ave the name 

 Hypogene, shows how modern science has already gone beyond 

 the theories of the great master. We observe a few paragraphs 

 in which the progress of science and even political classification in 

 the United States are disregarded. Thus " Freshwater strata of 

 western territories " and " greensands of New Jersey " give a 

 very inadequate notion of the present knowledge of the " Cre- 

 taceous " in North America (p. 336). The same remark applies 

 to " Limestones and shales of the Appalachians " as the only indi- 

 cation of the American representative of the lower Carboniferous 

 (p. 395). We notice (p. 431) that the " Calciferous sandstone" is 

 made to be the equivalent of the upper division of the Cambrian; 

 and the earliest trace of fishes is described as '' (?) Ordovician, 

 California," which probably refers to the Canon City, Colorado, 

 beds. Many valuable additions are made in the way of illustra- 

 tion to the 1871 edition of " The Student's Elements of Geology" 

 which formed the basis of the present volume. ' h. s. av. 



5. Chloritoid from MicMgan — a Correction^ by Wm. H. Hobbs. 

 (Communicated.) — In a paper published in this Journal (vol. 1, 

 p. 121, 1895, I mentioned the occurrence of a mineral in blocks 

 on the south side of Michigamme Lake, Michigan, and gave 

 sufficiently full chemical and optical data to determine it as chlo- 

 ritoid. Since the paper was published Dr. A. C. Lane has called 

 my attention to the fact that the chloritoid of this locality is 

 probably nearly or quite identical with that of the Champion 

 Mine described by Kellar and Lane in this Journal (vol. xlii, p. 

 499). A more careful examination of the mineral shows that it is 

 certainly triclinic as determined by Lane, the most important evi- 

 dence of this being the fact that prismatic sections which exhibit 

 the deep blue absorption of 6 have extinction angles with the 

 base of 20° or more. Figure 6 of my paper, which is drawn to 

 represent an approximately monoclinic mineral, is therefore incor- 

 rect as regards the crystallographic orientation. 1 should also 

 add that on page 31 of the filth volume of the Geological Sur- 

 vey of Michigan a reference is made by R-ominger to the occur- 

 rence of chloritoid in loose blocks south of Michio;amme A^illag^e. 

 This volume was issued shortly before my paper, but my efi'orts to 

 secure a copy had been unsuccessful. 



In a paper published as a bulletin of the University of Wis- 

 consin (Science Series, vol. 1, No. 4, p. 140) in enumerating the 

 several types of marcasite from the ore deposits of southern 

 Wisconsin and northern Illinois, one type (type 2) was mentioned 

 which was supposed, from the direction of apparent indistinct stri- 

 ations on the base, to represent a tabular type bounded on the 

 long edge by the macropinacoid. The crystals were very imper- 

 fect and almost completely altered to limonite. Subsequent 

 examination of similar but better specimens from the same local- 

 ity rcA^eals the fact that this type is produced by the distortion of 

 twinned individuals, the face marked a in the figure being not the 

 macropinacoid but the prism. 



