31 
Examples of Crinoids may be found under the Trenton forma- 
tion, in Alcove Case, No. I, and in Case c, Sect, i ; under the 
Hudson River group, in Alcove Case, No. 2 ; Niagara, in Alcove 
Case No. 3 ; a very fine series, perhaps the best in existence, 
from a New York locality, Lockport. Also from Waldron, Ind., 
in the same formation, a remarkably good series of illustrated 
examples, especially of Eucalyptocrinus, in Case E, Sect. 11. 
Among these are many of the roots of specimens of this genus 
showing the rootlets spreading in the shale like those of a plant. 
In Alcove Case, No. 4, are many internal casts of Crinoids, and in 
the Lower Helderberg formation, Case F, Sect. 10, are some very 
fine specimens ; see also Case h, Sect. 8 ; Case 1, Sect. 2, and 
Alcove Case, No. 9. Among the Crinoids of the Lower Carbon- 
iferous, special attention maybe directed to those of the Burling- 
ton and Keokuk limestones, Case M, Sects. 11 and 13 ; Alcove 
Case, No. 11, both sides, and Case n, Sect. 1. In this latter case 
there is preserved in alcohol an example of a species now living 
on the coast of Barbadoes, West Indies. Case N, Sect. 10, con- 
tains many forms from the Chester limestone ; and in Case R, 
Sects. 4 and 6, will be found a very fine slab of the Pentacrinus 
briareus, from the Liassic rocks, of Lyme Regis, England, and 
one of P. subangidaris from the same formation at Holzmiinden, 
Germany. 
BLASTOIDEA {Bud-like). 
These fossils, usually called PentremiUs, on account of their 
pentangular or pentalobate form, are generally small, and are 
known by the vulgar names "petrified hickory-nuts," or walnuts. 
They are very beautiful objects and somewhat resemble flower 
buds, hence the order name Blastoidea. The fossil, as it is usually 
seen, is only the body portion, which in life was supported on a 
slender stem, rooted to the bottom of the sea, or to foreign objects, 
like the true Crinoids; while instead of arms the ambulacra, or 
transversely grooved areas, were covered by very slender, thread- 
like tentaculae, which probably served the same purposes as did 
the Crinoid's arms. The following illustrations will give an idea 
of their forms. 
