32 Talbot — JVew York Helderbergian Crinoids. 



cular spot, generally dark-colored, which looks like the point 

 of attachment of the column to the crown. With the excep- 

 tion of this spot, the cleavage lines of the calcite have obliterated 

 all traces of organic structure. 



Horizon and locality . — At the base of the Becraft limestone, 

 or what was called the " Scutella limestone," at Clarksville, 

 Countryman Hill and Schoharie. 



Genus, Brachiocrinus Hall. 



Brachiocrinus {Herpetocrinus f) nodosarius Hall. Plate IV, 

 figures 7 and 8. 



Brachiocrinus n odosarius Hall, Nat. Hist. N. Y., Pal., vol. iii, 1859, p. 118, 

 pi. 5, figs. 5-7, pi. 6, figs. 1-3.- Waclismutli and Springer, Eev. Palaeocr., 

 Pt. II, 1881, p. 229 ; Proc. Phila. Acad. Nat. Sci., vol. xxxiii, 1882, p. 413. 



Herpetocrinus nodosarius Bather, Am. Geol., vol. xvi, 1895, p. 217. 



In Hall's description, these fragments of crinoids are consid- 

 ered as arms or parts of arms ; and this opinion was also held by 

 Wachsmuth and Springer, in 1881. Iu 1895, Bather brought 

 arguments to prove that they belong to columns, not arms,* 

 and even gave a revised diagnosis of these New York forms as 

 Herpetocrinus nodosarius. That he is not so certain of this 

 classification as the earlier paper would indicate, may be gath- 

 ered from the fact that in a later reference to the fossil, he lists 

 Brachiocrinus as doubtfully synonymous with Herpetocrinus. \ 



Among other points in support of his first view, he remarks 

 that " cirri composed of thick, beadlike joints which increase 

 in size from the base to the middle and thence diminish to the 

 extremities," characteristic of this species, are also found in 

 Herpetocrinus flabelliformis, which occurs in the uppermost 

 beds of the Silurian of Gotland. £ 



Most of the specimens in the Yale collection are so encrusted 

 with silica that it is very difficult to get anything but general 

 outlines; but one specimen is in fairly good condition and 

 clearly shows the joints of the column and. the cirri. The 

 joints are slightly wedge-form and quite thin, giving to the 

 fossil an irregular appearance, which is still further increased 

 by the difference in the size of the joints of the cirri. The 

 diameter of the cirri is so great that only every third or fourth 

 joint is cirrus-bearing. The bulb-like process, varying in size 

 and shape, is shown in several specimens at the end of the 

 column. The question has arisen whether this bulb is at the 

 base of the stem, or whether it is simply a thickening some- 

 where between the proximal and distal ends. If the latter 

 were the case, the central canal should show at both ends of 



* Am. Geol., vol. xvi, p. 213, 1895. 



t A Treatise on Zoology, Pt. III. The Echinoderma, p. 146, 1900. 



t Am. Geol., vol. xvi. pp. 215 and 216, 1895. 



