248 SMITHSONIAN INSTITUTION 



in the Keokuk. Among Camerata, Hall's "Actinocrinus" viminalis is an Amphoracrinus, 

 and his "A." daphne is a Cactocrinus — two genera which do not pass beyond the Lower Bur- 

 lington, and the latter of which is found in the Kinderhook of Iowa. "A." helice is an 

 Aorocrinus, a genus which begins in the Devonian and ends in the Upper Burlington. Not 

 a single species, or type, of the entire crinoidal fauna resembles in the slightest degree those 

 characteristic of the Keokuk. In 1902, in a letter to me discussing the subject, Professor 

 Herrick wrote : " You may quote me as verifying the Kinderhook age of the lower beds at 

 Richfield upon ample palaeontological evidence." 



Forbesiocrinus sp. 



Plates XXIII, figs. 11-13; XXIV, figs. 28, 29 



I have figured some fragmentary specimens from the Knobstone formation of Indiana 

 and Kentucky which while not sufficient for specific definition prove the presence of the 

 genus in those rocks. The fossils occur in thin bands of shale and limestone ; they are for 

 the most part much flattened, usually crushed so that on weathering they become disin- 

 tegrated and are found as scattered plates among the debris. The most careful search made 

 by three different collectors has thus far failed to locate the crinoids in place so that they 

 could be obtained in better condition by quarrying. These fragments were associated with 

 Wachsmiithicrinus, Mespilocrinus (both mainly Lower Burlington genera), and a large 

 assemblage of Inadunate and blastoid species of distinctly Lower Burlington and earlier 

 types. 



The most important of these fragments is the reconstructed ray, PL XXIII, figures 

 11a, b. It contains only the first four primary plates, and these not from the same indi- 

 vidual ; but the succession of interlocking angular faces for two ranges of interbrachials with 

 sutures of deep ligament fossae up to the middle of IBr„, followed by a corrugated margin 

 on the remainder of that plate and the axillary primibrach, shows beyond any doubt a struc- 

 ture identical with that of the type species. There is nothing else with which it might be 

 confounded. The relative thickness of the plates, 0.3 to 1 in width for the radial, is decisive 

 against their belonging to any Taxocrinus. The surface ornament is almost identical with 

 that of F. nobilis, and appreciably different from that of certain fragments from the same 

 locality which, on account of the greater thickness of the plates, I have referred to Taxo- 

 crinus (PL LIV, figs. 19a, b, c, 20). There was evidently a considerable variety of Flexibilia 

 in these beds, and if we had the specimens entire they would doubtless add much to our 

 knowledge of these forms. 



I also figure (PL XXIV, figs. 28, 29) two plates belonging to forms of this genus from 

 equivalent strata at Lake Valley, New Mexico; and another (PL XXIII, fig. 9) from 

 Fern Glen, Missouri. 



