LARVIFORM CRINOIDS 



11 



recently described species, doubt must remain. Aside from this point there 

 are two significant differences between A. austinii (restricted) and the other 

 crinoids. These are ( 1 ) the irregularly sized radials of the former, whereas 

 the radials of the latter are nearly of similar width even in those species 

 having axillary radials. The dissimilar radials in A. austinii would have 

 caused the oral vault, if present, to be distorted and unsymmetrical. (2) A. 

 austinii possesses five basal plates, but Wanner states that where the inter- 

 basal sutures are visible in the Timoran forms, the basal disc appears two- 

 fold, one suture lying in the right posterior radius and the other in the 

 anterior radius [17, p. 5]. It is probable that if any of the Timoran species 

 had possessed five basals Wanner would have observed the sutures in a few 

 at least of his numerous well preserved specimens. No basal sutures have 

 been seen in any of the American examples. 



The Timoran and American forms differ notably from each other in two 

 respects. ( 1 ) In the Timoran species the opening of the axial canal is at 

 the center of and interrupts the cross ridge of the articular facet and in this 

 respect is similar to A. austinii. In the American specimens, however, the 

 opening of this canal is behind the cross ridge and in the bottom of the 

 depressed muscle field, thus differing from the Scottish form. (2) The oral 

 domes of the crinoids from Timor are in general star shaped and pyramidal, 

 sloping more or less uniformly outward and downward to the radials. The 

 individual oral plates are convex, the depressions along the interoral sutures 

 forming radial furrows converging toward the center of the crown. In these 

 furrows the arms lay when contracted. The Russian A. multibracJiiatus is 

 probably also of this type. On the other hand, the oral domes of the Amer- 

 ican species are rosettelike and flat topped, the outside of the orals descend- 

 ing .abruptly to the radials below. Rather indistinct and steep radial furrows 

 are present between the outer edges of the orals but these do not converge 

 toward the center of the crown and between them the upper surfaces of the 

 orals are distinctly concave. The Russian species A. uralcnsis and its variety 

 nodocarinatus are apparently also of this type. 



An extended consideration of the facts presented above has resulted in 

 the conclusion that our species and probably those described by Wanner and 

 Jakovlev and the "immature" examples of Carpenter and Etheridge can not 

 be referred to Allagecrinus as typified by figures 2a, b, and c of Carpenter 

 and Etheridge's Plate XV. It is therefore necessary to erect a new genus, 

 Kallimorphocrinus, for a certain group having prominent oral crowns which 

 up to this time have been included under Allagecrinus and of which our 

 American species are typical. Whether or not the Timoran species should 

 be included in this new genus is undecided at present. 



As a result of the restriction of Allagecrinus austinii to the "adult" 

 forms of Carpenter and Etheridge and the introduction of a new genus for 





