92 The Amefican Geologist. August, i899 
of Martha's Vineyard and Block Island, Bulletin G. S. A., vol. viii, 
pp. 197-212, with maps and sections, March, 1897. 
Wright, G. Frederick. Some Remarkable Gravel Ridges in the 
Merrimack Valley, Proc. Boston Soc. Nat. Hist., vol. xix, pp. 47-63, 
Dec. 1876, quoting Clarence King, as before noted, the earliest rec- 
ognition of the terminal moraines of this district; The Kames and 
Moraines of New England, ibid., vol. xx, pp. 210-220, April, 1879. 
NOTICE OF A NEW DISCOVERY CONCERNING 
UINTACRINUS. 
By Frank Springer, Las Vegas, Now Mexico. 
Some recently acquired material from the Niobrara Chalk 
has disclosed a new and remarkable fact about this inter- 
esting fossil. The genus Uiiitacrinus has been hitherto de- 
scribed as possessing, below the radials, a single circlet of 
basals surrounding an undivided pentagon; this pentagon 
has been supposed to represent either the coalesced infra- 
basals, the proximal or terminal stem ossicle, or a mere sup- 
plemental plate developed to fill up the space left by the dis- 
appearance of the stem. It is now ascertained that the 
above structure, although frequent, is not a uniform charac- 
teristic of the genus. Some of the specimens have below 
the basals a ring of five infrabasals, and these in turn enclose 
the undivided pantagon, or centrale, — thus giving the basal 
structure of Marsupites. In this form the centrale cannot re- 
present coalesced infrabasals, for these are also present and 
surround it. Wachsmuth and Springer's law of the orienta- 
tion of the parts below the radials prevails here: the infra- 
basals are radial, while the centrale is interradial when the 
former are present, and radial when they are not, — just as 
the stem should be. We have here, therefore, the two dis- 
tinct types of base, monocyclic and dicyclic; and, what is 
most extraordinar}^, they occur among individuals not onl}' 
of the same genus, but apparently of the same species U. 
socialis. 
My purpose in this note is merely to record the fact, 
which will raise some interesting questions touching classi- 
fication. The proof of it, with sufficient details and illustra- 
tion, will be given in a paper now in preparation. 
