246 SMITHSONIAN INSTITUTION 



with a small one in second axil ; the remainder of the areas above this and those 

 in anal interradins followed by perisome. IBr 3 ; IIBr 4 or 5, with two or more 

 bifurcations beyond; rays strong at first, diminishing rapidly at each bifurca- 

 tion, and the divisions widely separated. Column expanding above, with very 

 thin ossicles which become longer and alternating after about the first twenty. 

 Limits and characters of tegmen unknown. 



Hall described under Forbesiocrinus communis two widely distinct species, his figure 3 

 being a Taxocrinus, while figures 4 and 5 fall under the above description. The specimens 

 occurred in a layer of bluish grey, argillaceous limestone in the lowest part of the Cuyahoga 

 shale at the base of the Lower Carboniferous. They were associated with a fauna which, 

 independent of the crinoids, was declared by the late Professor C. L. Herrick (who made a 

 special study of the Cuyahoga formation in connection with the Ohio Geological Survey) 

 to bear an " unmistakable resemblance to the so-called Sub-Carboniferous of Belgium, 

 especially to that of Etage I, the Limestone of Fornai [Tournai] " (Bull. Geol. Soc. 

 America, vol. 2, 1890, p. 39). The locality produced a considerable variety of crinoids, 

 and the specimens were well preserved, as may be seen by reference to those figured on 

 plates 11 and 12, vol. 2, of the Paleontology of Ohio. They were evidently deposited in 

 a fine, calcareous mud, upon a quiet sea bottom ; the calyx plates were but little disturbed 

 and usually the arms and stems were attached, although few in that state were secured by 

 the collectors. This matrix is rather firm and homogeneous, favorable to the preservation of 

 the finer parts, but its color is so near that of the fossils themselves that it is impossible to 

 clean them so as to show such delicate structures as the finely plated perisome ; but every- 

 thing in the way of solid plates can be uncovered with precision. 



The five specimens of this species figured herein have been cleaned with the utmost care, 

 with a view to ascertaining the exact nature of the structures between the rays. One effect 

 of this may be seen by comparing my figure $b on Plate XX with Flail's figure of the same 

 specimen on plate 12 of the Ohio Report, in which the anal structures above the posterior 

 basal are not shown at all, not having been exposed on the specimen until now. I mention 

 these details to support the statement that in my opinion the plates of the interbrachial and 

 anal areas shown by the figures are substantially all the solid plates existing in this form 

 between the rays, although I have not been able to actually identify the perisome connecting 

 with them. The series of plates following the first range of anal plates along the left margin 

 of the posterior ray are suturally united to it certainly to the height of the first secundibrach 

 (PI. XX, figs. 5Z7, 6, 7). The left margin of this series is rounded without the slightest indi- 

 cation of any angular or sutural face, but on the contrary it is just such an edge as we find 

 along the distal face of interbrachials in Onychocrinus and Taxocrinus, and at the margins 

 of the rays in Temnocrinns, where we know that perisome was attached. The same thing 

 is true of the other ray margins, which are all rounded with no sign of sutural attachment 

 above the interbrachial plate. These facts lead to the conclusion that the remainder of the 

 anal area was not filled by solid plates, but by perisome adjoining the margin of the series 

 of plates which we see in figures $b and 6. 



The superficial resemblance of this species to Temnocrinus is quite strong. A slight 

 upward extension of the anal series of the latter, and the interpolation of an infer-radial in 

 the four regular rays, will produce this form in all essential characters. It is well distin- 

 guished from the Belgian species by its single interbrachial and greater extension of the 

 dextral anal series, as well as by its smooth surface. 



Types. Hall's originals (PI. XX, figs. 4, 5) are in the New York State Museum at 

 Albany. The other specimens figured are in the author's collection. 



Horizon and locality. Base of Lower Carboniferous, Cuyahoga shale ; Richfield, Ohio. 



