A. Hyatt on the Beatricce. 263 
ponding to angular external ridges projecting from the outer 
surface, The spaces between the folds are acutely angular, and 
‘answer to an equal number of broad shallow channels between 
the external ridges. The correspondence of this core with the 
te 
tween the vacant, deeply cut, angulated interspaces, and the 
‘shallow, external channels, show that the inclosed body was sur- 
Tounded by amantle. If the shell had not been secreted by an 
‘tiveloping mantle, the outline of the exterior would have cor- 
Tsponded more closely to the internal irregularities of the sur- 
fice of the body, and there would have resulted a shell with 
‘prominent lobe-like folds, instead of depressed, angular ridges, 
ery cut angulated interspaces, instead of broad, shallow 
innels, 
re 
“Meroal, subepidermal, ornamented layer; features which he 
€rs as irreconcilable with the structure of that branch. 
Anad 
“rved within the chamber, the last of a series of other cone- 
it “ambers, when considered in connection with the contin- 
c the sub-epidermal layer, and the absence of all annular 
Nollast shows conclusively that the shell was secreted by a 
ok sn micee are very like the Hippuritidee, both in general 
nt hen 
