MOEPHOLOGTCAL PART. 51 



" Cheirocriniis " clarus,^ and in Eucalyptocrinm crassiis,^ 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 Eiicali/ptocriiiiis 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 wdiich the numerous branches were given 

 off in a similar manner as the immature cirri from the terminal plate of 

 " Cheirocriniis " dams. 



Among recent Crinoids, such terminal 23lates have been found in connec- 

 tion with fragmentary stems in Calamocrinus DiomedcB Agassiz-t 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 RJiizo- 

 crinus Raivsoni, 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 Palaeozoic 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 PentacrinidcB, and not essentially different from that of the free floating 

 Comatulae. This interpretation seems far more reasonable than the sup- 

 position that these Crinoids w^ere permanently attached. 



* New York State Cab. Nat. Hist. ; Fifteentli Rep., Plate I. Figs. 17 and 18. 

 t New York State Museum Nat. Hist. ; Twenty-eighth Rep., Plate 17, Pig. 5. 

 X On Calamocrinus; Mem. Mus. Comp. Zool., Yol. XYII. Plate 28, Pigs. 2, 3, 4. 

 § Chalk Rep. on Stalk. Crin. ; Plate XXX. a, Pig. 4. 

 11 Ibid. Plate LIII. Pig. 7. 



