396 PROCEEDINGS OF THE ACADEMY OF [1881. 



4. (?) HADE0CRINTJ8 Lyon. 



1869. Lyon. Trans. Amer. Philos. Soc, vol. xiii, p. 445. 

 1879. Zittel. Handb. der Palaeont., i, p. 377. 



Syn. (?) Coronocrinus Hall. Palaeont. New York, iii, p. 124. 



The name was proposed for certain crinoidal remains, which had 

 been obtained from the Devonian, near Louisville, Kentucky. 

 The specimens were all fragmentary, but enough is preserved to 

 show a great resemblance to Dolatocrinus, and it seems to us that 

 this form should be, like Stereocrinus, placed subgenerically under 

 it. Hadrocrinus differs from Dolatocrinus in the smaller size of 

 the basals, and in having only two primarj^ radials ; it differs from 

 this and Stereocrinus in the numerous bifurcations within the rays, 

 and in having the arms arranged continuously around the body, and 

 not in groups. The genus Coronocrinus proposed by Hall, which 

 was founded upon mere fragments, is in all probability identical 

 with Hadrocrinus. 



According to Lyon, the body is very large and broad, the calyx 

 low vasiform, the dome hemispherical. Basals three, small, hidden 

 by the column, and only seen when viewed from the inner side. 

 Primar}^ radials 2X5, the second axillary. Higher orders of 

 radials numerous, each one composed of two series, and the plates 

 all forming a part of the calyx. The uppermost plate excavated, 

 and forming with the dome plates a large ambulacral or arm 

 opening. The openings are numerous, arranged continuously 

 around the body, and are at no place separated by interradial pieces. 

 Interradial arese composed of few, three or four pieces, which, like 

 all the radial pieces, are comparatively narrow and long, and of 

 very uniform size throughout, thereby producing the great width 

 in the bod3\ It is not known whether the anal area is distinct or 

 not. Interaxillaries two to four or more. Arms unknown. 

 Column round, rapidly tapering downward ; perforation round 

 near the calyx, at a distance below pentalobate. 



Geological Position, etc. — From the Devonian of Kentucky. 

 We only recognize two of Lyon's species. Hadrocrinus penta- 

 gonus is very imperfectly known, and in all probability belongs 

 to a very different group. 



1869. Hadrocrinus discus Lyon. Trans. Amer. Philos. Soc, vol. xiii, p. 448, PI. 26, 

 fig. a. Corniferous limest., Devonian. Falls of the Ohio. 



1869. Hadrocr. plenissimus Lyon. Trans. Amer. Philos. Soc, vol. xiii, p. 445, PI. 

 26, figs. B 1-3. Corniferous limest., Devonian. Falls of the Ohio, near Jef- 

 fersonville, Ind. 



