260 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



base, are sliglitly tumid, their surfaces being rugose or wrinkled, and in 

 some if not all cases marked by obscure lines which radiate from the 

 center of each piece in groups of threes, and become continuous with 

 similar lines on adjoining pieces. 



Height from the base of the body to the base of the proboscis, 32 

 millimeters ; breadth of the same, ] 6 millimeters. 



Although this species serves as a very suggestive link between the 

 crinoidal fauna of the Upper Coal Measures and that of the Subcarbo- 

 niferous, especially that of the Burlington limestone division of that 

 series, it differs too much specifically from any described form embraced 

 by that genus to need detailed comparisons. 



Position and locality. — Upper Coal Measure, thirty miles west of Hum- 

 boldt, Kansas. See introductory remarks. 



Genus Aech^ocidaeis, McCoy. 



Archaeocidaris dininnii. Plate 1, figs. I'.i, 14, and 15. 



Principal spines fusiform, moderately strong, 50 or 60 millimeters 

 long, the greatest diameter being about the middle, which is there 

 about 5 millimeters. The diameter of the basal ring of such a specimen 

 is about 3J millimeters, and the short neck or j^lain space above it is 

 scarcely 2i millimeters in thickness. Above the short plain neck the 

 whole spine is studded with irregularly disposed spinules, 1 to 2 millime- 

 ters in length, which stand out at nearly right angles with the axis of the 

 spine, except near its point, where they are directed upward. The spi- 

 nules are usually more numerous and stronger upon the lower portion of 

 the spine than elsewhere, and upon the middle portion of the large 

 spines they are sometimes obsolete, apparently from some other cause 

 than accidental removal. The smaller spines are often not so thickly 

 studded with spinules as the larger ones, and they are usually more 

 slender or less fusiform than the larger; and some of them seem to 

 have been without a basal ring. 



A marked peculiarity of this species is the abundance of spinules 

 upon the spine, especially its lower portion, and the general position of 

 most of them at nearly right angles to its axis. 



Position aiid locality. — Uj^per Coal Measures, near Tecumseh, Nebras- 

 ka, whence it was sent with other Upper Coal Measure fossils by Mr. 

 Frank M. Dininny, in whose honor the specific name is given. This 

 species has also been recognized by me in rocks of that formation iu 

 other portions of Nebraska and also in Western Iowa. 

 . Washington, Novemher 8, 1879. 



