39G Dr. F. A. Bather on British Fossil Crinoids : 



is perhaps predominant ; it is seen, for instance, in E 21977- 

 21982, E 21984, E 22027. But the number 3 is also 

 common, and occurs in E 21983, E 21985-21993, E 21975. 

 Occasionally only one facet is found, as in E 21977 epizygal, 

 E 22027 hypozygal. Not a single specimen has more than 

 3 facets to the node. Meneghini {op. cii., pp. 40, 41) refers 

 to this species specimens from the Eocene of Albettone in 

 the Euganean Hills, one with 4, another with 5 facets ; but 

 his reference is unconfirmed. 



Only about half of those specimens in which one of the 

 svzvgial faces is preserved have the intersyzygium complete. 

 But those that have are enough to show that the cirri are 

 distributed according to a definite plan. When there are 

 three facets at one end, they are not adjacent, but one is 

 opposed to the two others, being separated from them on 

 each side by a blank radius. At the other end of the inter- 

 syzygium there will never be 3 facets, but only 2; and these 

 will occupy the radii left blank at the other end. The 

 arrangement may be symbolized thus : — 



A b C D e 



a B c d E 



The next case is when there are 2 facets at each end. 

 The arrangement then is 



a B c D e 



a 



b C d 



or 



A b C d 



In only one specimen, E 21984, does a facet appear to be 

 repeated on the same radius, thus : 



a B c D e 



A b c D e 



but the specimen has been shifted in the middle and pro- 

 bably twisted also. 



In the rare cases where only one cirrus was borne by 

 the nodal {e.g., E 21977), it seems to have alternated in 

 position with two at the other end, 



a B c D e 



a b C d e 



In E 22027, however, the single notch on the hypozygal is 

 on the same radius as one of the two facets on the epizygal. 



