﻿WOOD] MOW AND ol.D MIDDL1 devonic crinoids 67 



the plates between the nodes appears to have been ornamented by 

 fine ridges similar to those of Megistocrinus tuberatus n. sp., bul 

 this feature is not well preserved. 



* mim> 



Fig. 4.—Tylocrinus novas n. gen. et sp. Arrangement of calyx plates. 



Basals three ; radials five ; costals two times five. The right antero- 

 lateral ray is the only one having four arms. In this the distichals 

 bear on each axillary edge a first and second palmar. In the left 

 antero-lateral ray there is only one distichal and but two palmars, 

 though the second costal in this ray has the form of an axillary plate. 

 The form of this plate seems to suggest the possible crowding out of 

 the second distichal and the two arms required to make the right and 

 left antero-lateral rays correspond in structure. Palmars are absent 

 from the remaining three rays, the first distichal being followed by 

 one or two additional distichals, and these by the two arms of the 

 ray. The interbrachial formula is normally I, 2. 3, 2. but in the left 

 postero-lateral interray the brachial plates meet above the first inter- 

 brachial. probably a result of crowding due to the wide anal area. 

 There are two minute interbrachial s between the arm bases. A 

 variable number of minute interdistichals or interpalmars are present 

 in all but one of the rays. 



The anal interray is peculiar in possessing two plates in the radial 

 series. The formula for the succeeding rows of plates is 4. 4. 5. 4. 7. 

 The plates of the sixth row merge into those of the tegmen. 



Tegmen moderately elevated and formed of minute, strongly con- 

 vex plates. Anal tube subcentral. 



