REPORT ON THE CRINOIDEA. 147 
Paleocrinoids the distal faces of the radials remain permanently in the horse-shoe 
condition, and the ligaments and muscles must therefore have remained small and poorly 
developed, just as they are im recent Crinoids until the central canal is completely closed 
in. The gradual development of complete articular facets, commencing before the horse- 
shoe stage, has been traced in the radials of the Paleozoic Allagecrinus, just as in the 
Comatulz ;' and I see therefore no reason to doubt that many Palzocrinoids had an 
imperfect articulation and not a suture between the horse-shoe facets of the first two 
radials. This may perhaps be correllated with the small development of the arms of the 
Paleeocrinoids, relatively to that of the calyx. The integrity of long arms with two 
hundred or three hundred joints, like those of many Comatule, would be much more 
perfectly preserved if the bundles of muscles and ligaments were large and well developed 
than if they remained small, as must necessarily be the case on an imperfect terminal 
facet of a semicircular or horse-shoe shape. 
Believing then that in a very large number of the Paleocrinoids the second radials 
were at least as movable on the first as in Apiocrinus, and in some cases a good deal 
more so, I cannot regard the “ differentia” of the Palzeozoic and the later Crinoids on 
which Miiller and his followers laid so much stress, as a point of great systematic 
importance. 
Wachsmuth’ omits all reference to the mode of union of the plates in his diagnosis 
of the Paleeocrinoidea; and had it not been revived by Zittel as a means of 
distinguishing the two great groups, Miiller’s name would long ago have fallen into 
disuse. 
The name Palzeocrinoidea was proposed by Wachsmuth’ in 1877 to denote “all true 
Crinoids in which the actinal side is closed;” but it was not actually defined by him 
until two years later, nearly simultaneously with the appearance of Zittel’s classification. 
He regards the group as of sub-ordinal value, and as specially distinguished by two 
characters—(1) the interradials constitute important elements of the test; (2) the 
absence of external food-grooves or oral aperture. He proposed incidentally to group the 
later Crinoids together under the name “ Stomatocrinoidea”; but he did not attempt to 
define the group; and so far as I am aware, this name has not been adopted by 
systematic zoologists, while Wachsmuth himself is now inclined to abandon it. Various 
reasons, which will be explained more fully subsequently, have induced the writer to 
propose the name of “ Neocrinoidea” for the Mesozoic and later Crinoids. This has been 
adopted by Prof. Zittel, and also by de Loriol in his work on the French Jurassic 
Crinoids, and it will be used throughout these Reports. 
Although Marsupites is ranked among the Tessellata by Miiller, and also, together 
with Uintacrinus, by Schliiter and Zittel, I can see no reason for excluding these two 
1 Ann. and. Mag. Nat. Hist., 1881, ser. 5, vol. vii. pp. 283-287. 2 Revision, part i. p. 30, 
3 Amer. Journ. Sci. and Arts, vol. xiv. p. 190. 
