76 F. A. BATHER 



individuals, as supposed by C. A. White, Meek & Worthen, and 

 Etheridge & Carpenter. In E 30106 they are not preserved, but 

 the notches indicating a mobile articulation extend round the peri- 

 stone; in so young a form one would not expect these plates to 

 have been fused. 



The new material shows no traces of plates covering the anal 

 aperture, or of facets for plates of a tube raised above it as suggested 

 by Etheridge & Carpenter. 



The horizon of all specimens in the British Museum is given as 

 Lower Burlington. I do not find either the species or its supposed 

 variety recorded from any other horizon. It would, however, be 

 interesting to work out its vertical distribution with more accuracy, 

 and to see whether the earher representatives are closer to the 

 tumbler or bell-form of the smaller, and supposed younger, indi- 

 viduals in our series; and whether the later representatives are 

 closer to the parachute-form of the larger, and supposed older, 

 individuals. 



