MORPHOLOGICAL PART. 51 
“ Cheirocrinus” clarus,* and in Eucalyptocrinus crassus,t both described by 
Hall. In the former the plate is fixed to a stem fragment, and closely 
resembles the plate figured by us on Plate I. Figs. 9, 10, having like that 
small budding cirri. The Lwealyptocrinus is a young specimen, which may 
have perished before reaching the free stage. Detached roots of this species 
have been found in large numbers, even larger ones than that figured by 
Hall. In some localities they are so abundant that they lie in contact in the 
rock ; but they are very rarely associated with pieces of the stem proper, or 
with parts of the crown. These roots seem to have been derived from a 
central disk (dorso-central), from which the numerous branches were given 
off in a similar manner as the immature cirri from the terminal plate of 
“ Cheirocrinus”” clarus. 
Among recent Crinoids, such terminal plates have been found in connec- 
tion with fragmentary stems in Oalamocrinus Diomede Agassiz,£ and in Penta- 
crinus naresianus Carpenter, in which the stem increases in width downward ; 
but it is uncertain in both cases whether the stem is fractured or had been 
cast off by the animal. Different is the structure in a specimen of Phizo- 
erinus Rawsoni, figured by Carpenter, || in which it seems as if the dorso-central 
is unrepresented. There are given off from the sides of the last stem joint a 
few irregular cirri, directed downward, and the distal end of the joint is 
closed, as in the case of semi-free Pentacrinoids. The last joint differs in no 
other way from the joints above, and has the same form and length as the 
preceding one. 
Among Paleozoic Crinoids we have seen the complete stem in upwards 
of thirty specimens of various genera, but none of them had a dorso-central. 
or a surface for attachment; the stems invariably terminate in a point. The 
terminal portion, however, forms no part of the primitive stem, but is of 
later growth, and probably served the same purpose as the lateral cirri. 
Now if it is true that the young Crinoid was attached by a dorso-central, 
as we may suggest from the ontogeny and phylogeny of the group, then all 
these specimens are morphologically in about the same condition as the semi- 
free Pentacrinide, and not essentially different from that of the free floating 
Comatulx. This interpretation seems far more reasonable than the sup- 
position that these Crinoids were permanently attached. 
* New York State Cab. Nat. Hist.; Fifteenth Rep., Plate I. Figs. 17 and 18. 
+ New York State Museum Nat. Hist.; Twenty-eighth Rep., Plate 17, Fig. 5. 
+ On Calamocrinus; Mem. Mus. Comp. Zool., Vol. XVII. Plate 28, Figs. 2, 3, 4. 
§ Chall. Rep. on Stalk. Crin.; Plate XXX. a, Fig. 4. 
|| Ibid. Plate LIL. Fig. 7. 
