]881.] NATURAL SCIENCES OF PHILADELPHIA. 251 



The subgenus evidenth^ represents the mature and extreme 

 form of the Platycrinoid tj'pe. 



Geogi-aphical Position, etc. — Found as yet only in the Subcar- 

 boniferous of America, where the following species are known : — 



1878. Eucladoorinus millebracliiatus Wachsni. and Spr. Proc. Acad. Nat. Sci. 



Phila., p. 245. Upper Burlington and Keokuk Transition bed, ani lower 



part of the Keokuk limest. Burlington, Iowa, Nauvoo and Niota, 111. 

 1871. Eucladoor. inontanaeii<'is Meek. Ilayden's Geol. Rep. U. S. Surv. Terr., p. 



373. Subciirb. Montana. 

 1862. Eucladocr. pleuroviminus AVhite (Platycr. pleuroviminus). Type of the 



subgenus. Proc. Bost. See. Nat. Hist., ix, p. 17; Meek, 1870, Am. Jour. 



Sci. and Arts; AYachsm. and Spr., 1878, Proc. Acad. Nat. Sci. Phila., p. 249. 



Upper Burlington limest. Burlington, Iowa. 



6. (?) COTYLEDONOCRINTIS Casseday and Lyou. 



1860. Casseday and Lyon. Proc. Acad. Arts and Sci., v, p. 26. 



1865. Shumard. Catal. Pal. Foss. N. A. Trans. St. Louis Acad., ii, p. 360, 



1877. S. A. Miller. Catal. Am. Pal. Foss., p. 74. 



1879. Zittel. (DicJiocrinus.) Handb. d. Pal., i, p 365. 



Casseday and Lyon proposed the above name for a crinoid 

 which agrees in every respect with Dichocrinus, except that it 

 has no anal plate in line with the first radials. According to 

 the description, however, there is a deeper notch between the 

 radials on the posterior side, and the question arises whether the 

 type specimen was not an abnormal Dichocrinus in which the anal 

 plate was wanting or imperfectl}^ developed. The notch lies 

 directly in line with one end of the suture which divides the basal 

 disk, and hence the position corresponds to that of the anal in 

 Dichocrinus. The bipartite base itself seems to indicate that 

 there was normally a sixth plate above, for otherwise, according 

 to the rule we have found to prevail among these Crinoids, one 

 plate of the basal disk should be larger — while they are said to be 

 equal in this form. 



As described, Gotyledonocrinus agrees essentially in the form 

 of the body with typical species of Dichocrinus, and like them 

 has three primary' radials, the first large and long, the two others 

 small and supporting 2 X 10 secondary radials, succeeding radials 

 forming parts of the free rays. There is a single interradial in 

 connection with the first radials, two interradial plates above con- 

 stitute a part of the vault. 



The specimen has long delicate arms, which do not bifurcate, 



