A :ne\v rossiL crixcjid genus — kirk ,517 



and shorter, and the second bifurcation is liiohci' up. Tlii' dorsnl 

 cup of D. roemeri is badly preserved, and comparisons are of litth; 

 vahie. 



Ontogetnj. — The doi'sal cup in very yovui^; specimens is more ro- 

 tund and the plates less tumid tlian in the older specimens. The 

 Ix\x in youno- individuals., as is usnal, are proportionately lonu'er 

 and more slender than in older specimens. The same is also true of 

 the succeeding brachials. In young specimens the numl)er of IIBr 

 is six as a rule, though one half-ray seen had but four. The number 

 of IIBr increases M'ith age, the usual number in the largest speci- 

 mens being 10 or 12. 



There is a slight divergence of the rami resting on the IIx in 

 young and medium-sized specimens. With increasing age the axil- 

 lary faces of the IIAx tend to form a more acute angle. This throws 

 the bases of the terminal rami still farther apart. 



LITERATURE CITED 

 Teoost, Gerard. 



18.50. A list of the fossil crinoids of Teiuiessee. I'roc. Anior. Assoc. Adv. 



Sci. 1849, pp. .j9-64. 

 1909. A critical summary of Troost's niipiiblisliort mannscript on tluM-rinnids 

 of Tennessee. (Edited by Elvira Wood.) U. S. Nat. jNIus. P.uU. 

 64, xi-fl50 pp.. 15 pis. 

 Wachsaiuth, Charles, and SPKimiER, Frank. 



1886. Revision of tbe ralaeocrinoidoa : Pt. .3, sect. 2. Proc. Acad. Nat. 

 Sci. Philadelphia. 1886, pp. 139-334. (One nnnnmbered page in- 

 serted after p. 302. One inserted page, "Note to Page 2."t," which 

 appeared in two diiS'erent forms. Index to pts. 1-3, pp. 303-334.) 

 Wood, Elvira. (See Troost, 1909.) 

 WoRTHEN, Amos Henry. 



1882. Descriptions of fifty-four new species of crinoids from the lower 



Carboniferous limestones and Coal Measures of Illinois and Iowa. 

 Illinois State Mus. Nat. Hist. Bull. 1. art. 1, pp. 3-38. 



1883. Description of fossil invertebrates. Illinois Geol. Surv., vol. 7, pi. 



2, sect. 2. pp. 265-338, pis. 27-30. 



