36 



BKITISH FOSSILS. 



detailed are of very great weight, and that in the absence of contrary 

 evidence they must lead us to assign a place near, if not among, the 

 Siluroidei to Coccosteus. I do not know that any facts which 

 can be adduced can be fitly considered as such directly contrary 

 evidence, but there are several difficulties which require careful 

 consideration. 



In the first place, Coccosteus seems to have possessed neither 

 basal nor lateral cranial bones, — at least, no traces of such structures 

 have yet been discovered ; so that, in all probability, this fish 

 possessed a cartilaginous primordial cranium like that of Accipenser ; 

 and, indeed, a still more gristly one. for Accipenscv has a large 

 basal ossification. The hyomandibular suspensory apparatus must 

 have been equally cartilaginous, and, in the vertebral column, only 

 the superior and inferior arches were ossified. Assuredly this is 

 very unlike what we are accustomed to see among the Teleostei, 

 but it must be recollected that it is at least equally unlike what we 

 find in the Ganoids, if we except those of the same epoch ; and, on 

 the other hand, there are some recent Teleostei, though there are 

 no known Ganoidei, whose vertebral columns and skulls exhibit a 

 correspondingly low stage of organization.* 



In the second place, arises the question whether, since we know 

 that a true Ganoid, Amia, completely simulates the outward form 

 of a Clupeoid Teleostean, while retaining all the essentials of its 

 order, — may not Coccosteus be also a true Ganoid which simulates 

 the outward aspect of a Siluroid ? To this question it is, perhaps 

 impossible to give any answer, save by asking another, viz. : — Why 

 should not a few Teleosteans have represented their order among 

 the predominant Ganoids of the Devonian epoch, just as a few 

 Ganoids remain among the predominant Teleosteans of the present 

 day? When it is considered that an ichothyologist might be 

 acquainted with every fresh-water and marine fish of Europe, Asia, 

 Southern Africa, Southern America, the Indian Archipelago, 

 Polynesia, and Australia, and yet know of only one Ganoid, 

 the Sturgeon, a fish so unlike the majority of its congeners, that a 

 naturalist might be well acquainted with almost all the fossil 

 Ganoids, and yet not recognize a sturgeon as a member of the 

 group, — it will not seem difl^icult to admit the existence of a Tele- 

 ostean among the Devonian Ganoids, even though that Teleostean 

 should in some, even important, points differ from those with 

 which we are familiar. 



* See on this point, however, the remarks at p. 38, under (3). 



