OF CONCHOLOGY, 2t3 



" The inner septa, which supported the principal part of the 

 body of the Mollusk, form large cavities, while the second 

 part is made up of laminee laid on by the mantle margin, or 

 at least that part corresponding to the mantle margin of the 

 Lamellibranchiates. 



"In Beatriceae, on the contrary, the inner septa did not con- 

 tain the body of the animal, and there are no marks whatever 

 of a mantle margin. This objection could not be urged 

 against their affinity with Caprinella and the like, in which 

 the central cavities are small; but from these they may be 

 separated by the absence of all ligamental or muscular im- 

 pressions and the mode of forming annular, cellular partitions, 

 composed of numerous laminae, instead of a continuous series 

 of porous or tubular laminae. 



"The Hippurites, Gaprina, and the like, were, with few ex- 

 ceptions, attached to the surfaces upon which they lived or to 

 each other, and had short, thick, cone-like forms, affording 

 broad bases of attachment, whereas the Beatriceae were long, 

 thin, almost tubular bodies, resembling the Orthoceratites, and 

 entirely unfitted to support themselves in fixed positions. 



"We saw hundreds of ^. nodulosa and B. undulata 'in situ,' 

 but nowhere any indications of attachment, either to the rocks 

 or to each other. 



"After close comparison with all the types to which these 

 singular fossils appeared to have any resemblance, I have at 

 length considered myself warranted in considering them as 

 Cephalopods more closely allied to the genus Endoceras, than 

 to any other group of that class. 



" They differ greatly from all the Tetrabranchiates, in the 

 open structure of the partitions or septa between the chambers, 

 and this character, together with the absence of a siphon, and 

 the cone-like form of the septa, demands that they should be 

 separated as a distinct order, for which I propose the name of 

 Ceriolites. Although distinct as an order because of the dif- 

 ferences in the form and structure of the septa, arising from 

 their great length, and the loose way in which the laminae are 

 arranged, the parts may be compared point for point with 

 similar parts of Endoceras. 



" We may imagine the cone-like septa of a Beatricean to be 

 spread apart, until their surfaces should be parallel through- 

 out the shell; they would then be entirely separated by hollow 

 chambers, as the septa are in Endoceras, and if, at the same 

 time, the central cup-like cavities were supposed to be pro- 

 longed into cones, we should, without violence to the typical 

 idea of the organization, have transformed the Beatricea into 

 a shell separable from the Endoceras by only one character, 

 the vesicuiarity of the septa. 



