236 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Orals of rather irregular arrangement, and their identification sometimes 
difficult in certain species. 
Column circular ; the nodal joints considerably wider and higher, rounded 
at their edges; axial canal pentalobate or stellate, the angles directed 
radially. 
Distribution. —Gilbertsocrinus occurs in America and Europe. It first ap- 
peared in the Hamilton group, reached its climax in the two Burlington 
beds, and became extinct before the close of the Keokuk epoch. 
Remarks —The name Ollacrinus, the earliest name given to this form, 
was proposed by Cumberland in 1826, in an appendix to the Reliquize Con- 
servate. He published no generic diagnosis or specific name, but gave an 
excellent figure, by which the type is easily identified. Of the plate con- 
taining this figure, however, we have been informed by the late Dr. P. H. 
Carpenter that only a few copies were distributed in a private way, and that 
no copy of it is to be found in the Library of the British Museum.* For this 
reason it cannot be looked upon as lawfully published, and the name will 
have to be given up. 
Phillips proposed the genus Gilbertsocrinus in 1836. He included in it 
Cumberland’s type, which he described as G. calcaratus (Pl. XV. fig. 5). His 
ficures are fairly good, but the descriptions are meagre, and show no essen- 
tial departures from Lhodocrinus. Neither does he make any allusion to the 
two different sets of openings, which are so well represented in his figures, 
The arms are described as ‘‘ rounded and perforated in the centre.” 
De Koninck and Le Hon, in 1854. declared that Ollacrinus and Gilbert- 
socrinus were synonyms of Rhodocrinus. They probably arrived at this con- 
clusion from their ‘‘ Rhodoerinus stellaris,’ which we find to be a true Gilbert- 
socrinus (Pl. XV., fig. 4). Similar views were expressed by Roemer, Pictet. 
and Dujardin and Hupé. 
In 1859, Lyon and Casseday described a new species from the Carbon- 
iferous of Kentucky, and made it the type of a new genus: Goniasteroido- 
crinus. The species closely resembles that figured by Cumberland and 
Phillips, except that the supposed arms (appendages) are suturally connected 
by their sides, in pairs, for some distance; while those of the British species 
are separate from their origin, Lyon and Casseday’s specimen was in excel- 
lent preservation, the so-called arms being all in position, and it had below 
and between these “arms, in the interradial fields,” as they state, clusters of 
* We saw it in the Cambridge copy which was formerly in De Koninck’s library. 
