WHITE.] CARBONIFEROUS FOSSILS. 131 
ARCHZOCIDARIS DININNIL White. 
Piate 35, figs. 6 a, b, and ¢. 
Archeocidaris dininnit White, May, 1880, Proc. U. 8. National Museum, vol. ii, p. 260. 
Principal spines fusiform, strong, 50 or 60 millimeters long, the great- 
est diameter being about the mid-length, and about 5 millimeters. The 
diameter of the basal ring of such a specimen is about 33 millimeters, 
and the short neck or plain space above it is scarcely 24 millimeters in 
diameter; above the short, plain neck the whole spine is studded with 
many irregularly disposed spinules, one to two millimeters long, which 
stand out at nearly right angles with the axis of the spine, except near 
its point, where they are directed upward. The spinules are usually 
more numerous and stronger upon the lower portion of the spine, and 
upon the middle portion of some of them the spinules are obsolete, ap- 
parently from some other cause than.accident. The smaller spines are 
usually more slender or less fusiform than the larger, and some of them 
seem to have been without a basal ring. Nothing is satisfactorily 
known concerning the body plates. 
A marked peculiarity of this -species, and one which makes it easily 
recognizable, although the other parts are unknown, is the abundance 
of spinules upon the spines, especially the lower portion, and the posi- 
tion of most of them being at nearly right angles to the axis of the 
spine. 
Position and locality—Upper Coalmeasures, near Tecumseh, Nebr., 
whence they were sent by Mr. F. M. Dininny, together with several 
other well-known Upper Coalmeasure forms. It is in his honor that 
the specific name is given. This species has also been recognized by 
myself at several localities in lowa and Nebraska. 
POLYZOA. 
Genus PTILODYCTIA Lonsdale. 
PTILODYCTIA TRIANGULATA White. 
Plate 33, figs. 3 a, b, ¢c, d, and e. 
Ptilodyctia triangulata White, 1878, Proc. Acad. Nat. Sci. Philad., 1878, p. 35. 
Ptilodyctia triangulata White, 1879, Bull. U. S. Geol. Sur. Terr., vol. v, p. 214. 
The type specimens of this species were obtained from the Coal-meas- 
ure strata at Danville, Ill., by Mr. William Gurley, and described by 
me in the place above cited. Some examples in the collections of the 
survey were obtained by myself from the middle division of the Carbon- 
iferous series on Yampa Plateau, Northwestern Colorado, and others 
were obtained by Mr. W. H. Holmes in the region southward from the 
Yellowstone National Park. These examples show that the corallum is 
ramose, as it was supposed to be when the species was originally de- 
scribed, although that fact was not clearly shown by the type speci- 
mens. The characteristics of the Colorado examples are in all respects 
like those of the type specimens, except that parts of the corallum are 
more slender, their sides having a breadth of from 2 to 23 millimeters 
instead of from 3 to 5 millimeters, as in the type specimens; but this is 
