264 A, Hyatt on the Beatrice. 
rite as to the Cephalopod. The shell of the Hippurite is com 
posed of three parts: first, the inner septa, second, the outer lay- 
ers, which frequently form a porous mass,’ and third, an external 
sub-epidermal layer.® a 
he inner septa, which supported the principal part of the 
body of the Mollusk, form large cavities, while the second = 
is made up of laminz laid on by the mantle margin, or at least 
that part corresponding to the mantle margin of the Lamelli 
branchiates. : 
In Beatriceze, on the contrary, the inner septa did not contain 
the body of the animal, and there are no marks whatever of @ 
mantle margin. This objection could not be urged against their 
affinity with Caprinella and the like, in which the central cavi- 
ties are small; but from these they may be separated by the abe 
sence of all ligamental or muscular impressions and the mode of 2 
forming annular, cellular partitions, composed of numerous lam- ' 
inge, instead of a continuous series of porous or tubular lamine. ; 
The Hippurites, Caprina, and the like, were, with few a ae 
tions, attached to the surfaces upon which they lived or to 
considered myself warranted in considering them as Cepha other 
They differ greatly from all the Tetrabranchiates, 1n the ri os 
structure of the partitions or septa between the aren re 
cone-like form of the septa, demands that they should cong . 
Ss icean to be 
We may imagine the cone-like septa of a SS ee 
spread apart, until their surfaces should be parallel by hollow 
the shell; they would then be entirely separated OY es 
, iy! rato Hippuritide. Quar. Jour. Geol. Soc.; London. v- 15, Pat 4 
page 41. : 
* Woodward. Quar. Jour. Geol. Soc., p. 46. 
* xnpvov, a honeycomb, 190s, a stone. 
