IIETEROCRINIDAE 
103 
That is to say, in the opinion of the author himself, species having the axil-arm system, 
borne on short faces of successive axillaries, arching around to the anal side — Forms C and D 
of my diagrams — do not belong under Deltacrimis, and should be separated from it 
genericallyd 
Therefore, whatever else D eltacrinus may be, it cannot include the Silurian species which 
come under Form C. They are, however, clearly covered by the genus Calceocrinus Hall, if 
not as described and figured by him in 1879 Ruder the name Calceocrinus stigrnatus, then 
certainly as amended and redescribed by Ringueberg in 1889 under C. halli as the original 
unnamed species of Hall, and a new species, C. typus, showing the correlated characters, for 
a genotype. I have no doubt that Ringueberg’s identification of Hall’s original Calceocrinus 
was correct, and that it is congeneric with C. halli and C. typus (pi. 29, figs. 17, 18, 19). There 
are two known generic forms of the hinged crinoid in the New York Silurian, and they can 
be distinguished by the base alone, without the aid of other charaqters : 
1. With 4 basals ; in which the two left basals, those in the middle next to the hinge, 
retain the characters of the Ordovician form, being in contact with the stem by their narrow 
points, their outer sides making a sinuous curve, and being still divided but with a tendency 
to coalesce and their dividing suture to become obsolete. This is Hall’s Chcirocrinus (Eucheiro- 
criniis M. and W.). His figure in the 13th Report, i860, page 123. is incorrect in that it does 
not show the two small basals touching the stem-facet or divided, though it does indicate the 
curving of the sides ; but both the missing characters appear in the type specimen, as here 
figured, plate 29, figure ic, confirmed by numerous other identical specimens from the same 
locality, some of them figured by Ringueberg (his pi. 10, figs. 6, yb, 13), and herein (pi. 29, 
fig. 2). Errors in the original description or figure due to incorrect observation or imperfect 
material cannot control the definition where the actual fact is shown by the tvpe and identical 
specimens. The habitus of this base is thoroughly characteristic, recognizable at a glance; 
any New York Silurian species with that type of base must be Chcirocrinus, and any one with 
a different type of base cannot be Chcirocrinus. 
2. With 3 basals ; in which the two left basals are detached from the stem and fused 
into a single triangular plate. Any species with such a base cannot be Cheirocrimt-s as deter- 
mined by the type, regardless of how the name may have been applied by authors, including 
Hall himself, who listed species having both forms of base under Chcirocrinus of the 13th 
Report., and shifted them to Calceocrinus in the 28th Report. But such a base is precisely that 
of Calceocrinus halli, C. typus, or any of the numerous species falling under Form C (perhaps 
excepting one in Gotland). Hall’s original Calceocrinus must be one or the other of these two 
forms. His figure (Pal. New Yoi'k, 2, pi. 85, fig. 5) shows a base with a triangular plate 
fitting into a much larger somewhat lunate-shaped piece, having the column-facet widely 
separate from the triangular plate (pi. 29, fig. 18). The description speaks of only two plates 
visible, but adds that the plates are so closely anchylosed as to obscure or obliterate the lines 
of suture. 
The fact that he mentions only two plates is not material, for we know there must have 
been a suture from the apex of the triangle through the stem-facet, as is the case in every 
species of the entire family ; so that the lunate-shaped piece into which the triangular plate 
fitted necessarily consisted of the two large basals, making the three which were correlated 
with the axil-arm system of Forms C and D. It is immaterial, because the undivided trian- 
gular plate is the decisive character, which excludes Cheirocrinus, defines what the original 
Calceocrinus is, and determines the fact that it must be congeneric with C. halli and C. typus. 
It cannot be anything else. 
Therefore Ringueberg’s identification of Calceocrinus as his C. halli was founded upon 
an unmistakable diagnostic character of generic value, clearly expressed in the original de- 
1 Dcltacrinus dactylns and D. nodosus, Smithsonian Misc. Coll., vol. 76, No. 3, 1923, p. 19, pi. 5, figs. 20, 
21, should be written Halysiocrinu.';. 
