262 A. Hyatt on the Beatricee. 
causes, not affecting any individual asa whole. In B, nodulosa 
they remain, with but few exceptions, constantly concave, and 
have regular fornis. ; 
2. e coniform layers are separated in fully grown spec 
mens by intervening spaces near the ike 
laminee. 
(8.) The sub-epidermal or outer layer is of a dark brown 
and in well preserved specimens is ornamented and conti 
without annular marks or furrows. 
) . 
they are composed; and the annular appearance is conseqi 
to the overlapping of the cone-like concentric pari a 
were deposited from within, and cannot, therefore, be consider 
plant-like exogenous layers. : B 
e were fortunate enough to obtain a specimen of ‘ie pa 
lata at English Head which demonstrates that the cone-} go : 
. 
titions are the walls of chambers that were successlvey ' 
