368 TRANSACTIONS OF THE CANADIAN INSTITUTE. {[Vou. VIII 
Protaster flexuosus, Miller and Dyer, cannot be retained as no infor- 
mation as to the shape of the ossicles ventrally was determinable from 
the type specimens. 
Protasterina fimbriata, Ulrich, has hour-glass shaped ossicles, and 
must therefore be dismissed. 
Protaster granuliferus, Meek. This species may be retained as the 
ossicles are said to be “longer transversely than in the direction of the 
length of the arms; each largely excavated at its outer anterior end, so 
as to form a large pore or pore-like depression, and divided transversely 
by a furrow into two parts.” It is evident that this excavation of the 
ossicle would give it a boot-shaped appearance. 
Protaster miamtensts, Miller, must be removed as the ossicles are 
described as subquadrangular. 
Tentaster elegans, Miller. From the description and figure this form 
would seem to be a true Profaster but for the fact that no disc is present. 
From the great similarity to the form about to be described, it seems to 
the writer that a disc had been present in Miller’s species but was lost. 
There can be no doubt that the form and arrangement of the 
ambulacral ossicles forms the best basis of classification for ‘the 
Paleozoic Ophiuroida. It is very doubtful, however, if a true concep- 
tion of this form can be arrived at by an inspection of the ventral aspect 
alone. From subquadrate to boot-shaped ossicles all sorts of inter- 
mediate shapes are obtained, depending on the degree to which the pore 
has encroached on the outer anterior angle of the original subquadrate 
body. In the species about to be described the “ toe” of the boot is 
much shorter than in the genotype and the dorsal aspect reveals the 
ossicles with an entirely different appearance. In order to arrive at a 
true conception of the shape of these bodies, sections were made across 
the arm. The result of this investigation was so important that it has 
resulted in the extension of this article beyond the mere description of 
the species as was first intended. 
PROTASTER WHITEAVESIANUS, sf. nov. 
The species is founded on four specimens, one showing the dorsal 
and three the ventral aspect. There are five tapering arms and a well 
marked disc. The size of all the specimens is approximately the same, 
but the one exposing the dorsal surface is alone perfect enough to afford 
