Kimball — Siderite-basins of Hudson River Epoch. 155 



sixteen millimeters long and three or three and one-half wide. 

 The spines are three millimeters long, directed somewhat dis- 

 tally and a little reflexed. So far as the specimens can be 

 made out, they agree well with Prof. Lapworth's figure of the 

 ventral aspect of G. Hincksii Hopk. (sp.).* The species of 

 this genus require revision, but its American representatives 

 are not yet fully known. 



At the localities near Albany, beside a very abundant Glosso- 

 graptus which is perhaps a small form of G. ciliatus Emmons, 

 there is an oddly irregular shaped form, that in some respects 

 approaches G. pinguis Hopk. (sp.).f Figure 16 of Plate B, 

 Graptolites of the Quebec Group, seems to represent this peculiar 

 graptolite in a spineless condition and small. 



No. 6 somewhat resembles Mr. Carruthers' figure of the 

 young form of Cryptograptus tricornis Carr (sp.)4 but is a 

 little longer in proportion to its width, and the sides do not 

 diverge quite so rapidly. I have no opinion to express as to 

 its relations. 



The G-raptolite compared in 1881 to Dicranograptus ramo- 

 sus probably can not be identified. There is no Phyllograptus 

 among my specimens. 



Cambridge, Mass. 



Aet. XV HI. — Siderite-basins of the Hudson River Epoch • 

 by James P. Kimball. With Plate VI. 



The Taconic region on the borders of western New Eng- 

 land and eastern New York has ceased to be the debatable 

 ground it once was, thanks to Prof. James D. Dana and to 

 collaborators in special parts of the same field — notably, the 

 late Rev. A. Wing on the limestone region of Vermont, Prof. 

 W. B. Dwight in Dutchess County, N. Y., and the excellent 

 work of C. D. Walcott. The unity of the limestones with the 

 Calciferous, Chazy and Trenton formations, appearing in 

 widely different aspects at intervals over this extensive area ; 

 the identity of its associated series of shales, grits, sandstones, 

 etc., with metamorphic products like fissile slates, hydro-micas, 

 schists, quartzites, and even gneisses ; and the relations of part 

 of the schists with the Hudson River group of strata have 



* Graptolites of County Down, Proc. Belfast Naturalists' Field Club, 1876-7, 

 Appendix IV. plate vi, fig. 24a. 



f For the opportunity to study this and a number of other interesting grapto- 

 lites, some of which will probably prove to be new or previously unknown in 

 New York rocks. I am indebted to the kindness of Mr. Charles Schuchert. 



\ Trans. Roy. Phys. Soc. Edinburgh, 1858, p. 468, fig. 2; Annals and Mag. Nat. 

 Bist. (3), hi, p. 25; Geol. Mag. 1868, V, Plate V, fig. 116. 



