368 PROCEEDINGS OP THE ACADEMY OP [1881. 



horizontally at right angles to the -walls of the body, without 

 bifurcations, and, according to figure, without pinnules. 



Judging from this description, the double-jointed arms are the 

 only characters which distinguish the genus from Glyptocrinus. 

 The next two species referred to Glyptaster were O. occidentalis 

 and G. inornatus^ both described by Hall from the Niagara gr. of 

 Waldron, Ind. In these specimens, which are found rather 

 abundantlj'^, only the calyx was preserved, while the vault and 

 arms remained unknown, thus leaving it somewhat doubtful 

 whether the two Waldron species may not be generically distinct 

 from the New York form. 



Glyptaster is closely allied to Eucrinus Angelin, indeed so 

 closely, that we have some doubt whether the two should not be 

 altogether united instead of being separated subgenerically, as 

 now pursued by us. So far as known, the latter form differs onl^^ 

 in having tertiary radials and additional arms. It is possible that 

 Glyptaster penfangularis Hall and Glyptocr. armosus McChesney 

 belong to the subdivision, the two species are only known from 

 internal casts, which are unreliable for purposes of identification, 

 unless accompanied by a cast of the external mould. 



In a ver}' interesting specimen of Glyptaster inornatus, kindly 

 loaned us by Mr. Wm. F, Gurley, of Danville, 111., and the only 

 specimen known to us in which the vault and anal aperture have 

 been found preserved, we notice in two of the rays on the side 

 toward the interradial spaces, and enclosed by them, a highly 

 elevated fixed pinnule. The specimen is of comparatively large 

 size, and as the interradials in this species have no conspicuous 

 surface markings, these pinnules are readily recognized. Both 

 are given off from a first secondar}'^ radial, which thereby takes 

 the form and aspect of a bifurcating plate. The first joint of the 

 pinnule is rather large, and the ridge or elevation upon the plate 

 is about one-half the width of that upon the radials. Two more 

 joints follow, likewise enclosed within the body walls, and having 

 a ridge equally conspicuous, though narrower. From the first 

 joint of the pinnule is given off another or secondary pinnule, 

 fixed like the other but more slender, and composed of at least . 

 two joints. The first plate of the primary pinnule has altogether 

 the appearance of a tertiary radial, and is given off in a like man- 

 ner, but the succeeding plates, though somewhat larger than 

 common, resemble more those of ordinary pinnules, or may be 



