ICHTHYOCRINIDAE 329 



Like W. thiemel, this species includes two or three forms which might be separated, but 

 the specimens occur in a limited horizon, and the range of variation is about the same as in 

 that species. Superficially the specimen represented on Plate XLIII, figure 14, looks very 

 different from the type, but the surface characters of the former have been removed by 

 erosion ; the two are much more alike in essential features than they are like figure 15, which I 

 should not hesitate to separate on account of its diverging arms and very long intervals 

 between ramules, if we did not have the same variations m. W. thiemei. 



None of the Knobstone specimens show any interbrachial plates; the spaces in figure 15 

 were probably not so occupied, as the margins of the brachials are rounded, and show no sign 

 of sutural faces. The young specimen, figure 13a, b, is interesting as showing the completely 

 different proportions of the plates from those of mature forms. Although the basal plates 

 are usually prominent in young individuals, they are in this one completely hidden by the 

 column, thus confirming the great reduction of these plates which is characteristic of the 

 species. 



As all the specimens are flattened I have given an outline restoration of the type, 

 accurately drawn to scale. 



Types. The original of figure II, is in the University of Chicago; the others in the 

 author's collection. 



Horizon and locality. Base of the Lower Carboniferous, Knobstone Group (New 

 Providence shales) ; Clark County, Indiana; Bullitt and Lincoln counties, Kentucky. 



Wachsmuthicrinus thiemei (Hall) 

 Plate XLIII, figs, i-io 



Forbesiocrinus thiemei Hall, Jour. Boston Soc. Nat. Hist., VII, 1861, p. 317; Descr. New Species Crin., 

 p. 8 ; Bull. I, New York St. Mus. Nat. Hist., Photographic Plates, 1872, pi. 7, fig. 4. 



Taxocrinus thiemei, Meek and Worthen, Proc. Acad. Nat. Sci. Philadelphia, (2) IX, 1865, p. 139. — Meek, 

 Amer. Jour. Sci., (3) VII, 1874, p. 191. — Wachsmuth and Springer, Revision Palaeocrinoidea, I, 

 1879, p. 49 ; N. A. Crinoidea Camerata, 1897, p. 139. — Whiteaves, Contrib. Canadian Palaeontology, 

 I, pt. 2, 1889, p. 94. — Keyes, Geol. Surv. Missouri, IV, 1894, P- 22 3> pi- 3°. fig- 5- 



Rhodocrinus (Taxocrinus) thiemei, Shumard, Trans. Acad. Sci. St. Louis, II, 1866, p. 398. 



Wachsmuthicrinus thiemei, Springer, Amer. Geologist, XXX, 1902, p. 96; Jour. Geology, XIV, 1906, 

 pi. 6, fig.. 19. 



Not Taxocrinus thiemei, Meek and Worthen, Geol. Surv. Illinois, V, 1873, p. 399, pi. 4, fig. 1. 



Type of the genus. 



A medium-sized species. Crown elongate, spreading upward ; widest about 

 first ramule, where height to width is 1 to 1.5 ; spread of calyx to that level from 

 outside of truncate base, I to 3. Cross-section at I Ax sharply pentagonal, side 

 outline to that level a notched line with little curvature. Base excavate, with 

 RR projecting slightly downward from the margin. .Sutures sinuous. Surface 

 smooth or finely granular. Mature crown, 33 mm. high by 24 mm. wide ; base, 

 8 mm. ; column at base, 5 mm. 



IBB small, within ring of BB, sometimes with a slight flange projecting 

 under BB. BB projecting in triangular points beyond the column. iBr 1 or 2 

 small plates, or absent. RR and IBr sloping to a sharp, angular longitudinal 

 median ridge, with more or less prominent angular nodes; they increase regu- 

 larly in width upward except when an interbrachial is present, when the first 

 primibrach is the shortest of the three plates. IIBr 3. Rays and their divisions 



