REPORT ON THE CRINOIDEA. 189 



case with some of the following extiuct forms," viz., Cystidea, Edriasterida, and 

 Blastoidea. 



The difference in the functions of the water- vascular system between the stalked and 

 the unstalked Echinoderms respectively was applied by Prof. Ray Lankester for 

 systematic purposes in his division of the Echinoderms into AmhulacraUa and Tenta- 

 culata, the latter including Crinoids, Cystids, and Blastoids.^ 



The name " Tentaculata " is unfortunately open to the objection that even in recent 

 Crinoids some of the radial water- vessels may be totally unprovided with tentacles at theii- 

 sides ; while if, as I believe, the water- vessels of the Blastoids occupied the subambu- 

 lacral canals within the lancet-pieces,^ they must certainly have been non-tentaculate. 

 To one division (class) of the group, therefore, the name " Tentaculata " would not be at 

 all applicable. Neither do I like the extension of the term " Crinoidea" to the Blastoids 

 and Cystids, and the consequent limitation of the brachiate forms by the name 

 Eucrinoidea, which we owe to Zittel so far as I have been able to trace it ; though it has 

 recently been adopted by de Loriol. 



In Miller's original definition of the Crinoidea^ he described them as having "a cup- 

 like body containing the viscera, from whose upper rim proceed five articulated arms, 

 divided into tentaculated fingers more or less numerous." The presence of these arms is 

 essential to the idea of a " lily-shaped animal." The very characteristic appearance of 

 the Crinoid typ)e is lost if the arms be not attached to the calyx ; while morphologically 

 they are of the utmost importance. 



On the other hand, jointed appendages of this kind, attached to the rim of the cup, 

 and containing radial extensions of the nervous axis of the stem, as well as of all the 

 ambulacral structures which surround the peristome, together with the genital glands, are 

 entirely absent both in the Blastoids and in the Cystids. In the former group, it is 

 true, there were jointed appendages at the sides of the ambulacra ; but although the 

 latter are very often spoken of as "recumbent arms," they are not composed of articulated 

 pieces, and only a very general homology can be traced between them and the branching 

 arms of a Crinoid. In the Cystids, however, segmented arms somewhat like those of 

 Crinoids seem to have been occasionally present, and even grooved by the ambulacra. 

 But they were mostly attached somewhat irregularly in the neighbourhood of the mouth, 

 and not to the radial portions of the cup as in the Crinoids ; and I much doubt whether 

 their component segments were regularly articulated together. 



Neither the Blastoids nor the Cystids, therefore, can properly be classed as Crinoidea, 

 in the sense of Miller's definition of the group ; though this has been very frequently 

 done during the last forty years, more especially hj continental naturalists. Von 



1 Notes on Embryology and Classification, Quart. Journ. Micr. Sci, 1877, vol. xvii., N. S., p. 444. 



2 On Certain Points in the Morphology of the Blastoidea, Ann. and Mag. Nat. Hist., 1881, ser. 5, vol. viii., p. 420; 

 Ibid., 1882, vol. ix. p. 218. 



5 Op. cit., p. 7. 



