CLASS III CRINOIDEA 227 



in pelagic forms, massive, and, except in the pelagic forms, much reduced in size. 

 Badials and arm-plates perforated hy separate dorsal canal. Base in most cases 

 actually or potentially dicyclic ; the infrahasals, and sometimes also the hasals, 

 being often atrophied, radically altered by resorption and subsequent rebuilding, or 

 absent altogether. 



Proximal columnal always modified, usually enlarged, attached to the 

 calyx by close suture, to the columnal below it also by close suture (the 

 so-called stem-syzygy) ; but this pair of columnals in some forms, instead 

 of maintaining the original connection with the calyx, is separated from it 

 by varying intervals in the stem, or at least in its proximal portion. Union 

 between the plates of the dorsal cup is by close suture, between the radials 

 and the primibrachs by muscular articulation, and between the elements of 

 the primibrach series by non-muscular articulation. Eadials always in lateral 

 contact. Eadianal and anal plates may be represented as such in the larval 

 stages, but never in the adult ; and the anal occasionally develops into a sup- 

 plementary radial, bearing a typical post-radial series indistinguishable from 

 those on the other radials. Arms uniserial and pinnulate, though the basal 

 pinnulation is often defective. No concavity in the apex of the dorsal cup 

 for the reception of the stem. Stem reduced to a single columnal in the 

 Comatulid division of this order. Lias to Recent. 



In tlie earlier German and English editions of this work, following the example 

 of previous European authors generally, the Mesozoic and Recent Crinoids (excepting 

 Marswpites, Uintacrinus, and perhaps Encrinus) were treated as a distinct group from 

 the Paleozoic under the name Articulata, proposed by J. S. Miller for the Apiocrinidae, 

 Encrinidae and Penfacrinidae, and extended by Johannes Miiller to include the 

 Comatulids. The chief characters relied upon to distinguish the order, viz. (1) an 

 open mouth and food grooves, (2) a separate axial or dorsal canal perforating the 

 arms, were admittedly indecisive, considering that the first belongs ec^ually to the 

 entire Paleozoic group Flexibilia, and the second is shared by a Devonian family and 

 several genera of the Inadunata. 



This evident inadequacy of the definition has led to various proposed substitutes 

 for the plan, such as placing the Pentacrinidae under the Fistulate Inadunata, and 

 the Comatulids together with the Apiocrinidae, etc., as a subdivision (" Pinnata ") 

 under the Flexibilia. None of these has proved satisfactory ; least of all the last, 

 for the lack of any sirfRciently definable connection between the so-called Pinnata and 

 the Paleozoic Flexibilia. The very j)liant calyx of the latter recurs in the pelagic 

 Comatulids, Marsupites and Uintacrinus, and the close lateral union or partial 

 incorporation of lower brachials is found to some extent among the Apiocrinidae, 

 Pentacrinidae, and some Comatulids. But it has become increasingly evident that 

 the Flexibilia were a specialised group, derived from the Inadunata, and ending like 

 the Camerata with the Paleozoic. 



The only one of the primary divisions of the Crinoids that seems to have survived 

 is the Inadunata, the most generalised type, from whij^i all the post-Paleozoic forms 

 are evidently descended. While, therefore, there is no valid ground for any such 

 divisions as Paleocrinoidea and Neocrinoidea, as j>roposed by Wachsmuth and Spiinger 

 and by Carjjenter, but afterward abandoned, yet it cannot be denied that, with the 

 sole exception of the Triassic Encrinus, the known Crinoids of Mesozoic to Recent 

 times have an assemblage of features by which they are In'oadly distinguished from 

 their Paleozoic ancestors. And it is believed that this may be expressed under the 

 group Articulata as enlarged Ijy Johannes Miiller, distinguished not by any single 

 character peculiar to itself, but by the fact that a large number of charactei's belonging 



