CLASSIFICATION OF DEVONIAN FISHES 455 
the urohyal of the Siluroid, the antero-lateral piece with the “ coracoid,” 
and the postero-lateral piece with the so-called “radius,” the more 
especially as the antero-lateral piece corresponds with that part of the 
thoracic shield of Pterichthys which supports the plated appendage 
representing the pectoral fin, in that genus. 
On the other hand, it must be confessed that the closer connexion 
of the antero-median piece with the thoracic plates than with the 
hyoidean cornua, and the very backward position of the postero-lateral 
plates, apparently out of reach of any connexion with the fins, militate 
against this view ; which, in addition, leaves the median rhomboidal 
plate unaccounted for. 
The bones Mn. are, of course, as has long been determined, the 
rami of the mandibles of Coccosteus. Their singular figure is not un- 
like that of the corresponding bones in Loricaria. Finally, the long 
Fig. 21. Hyoidean and Pectoral Plates of Clardas, Coccosteus, Lortcarta. 
flat bones a (fig. 21), I have no doubt, are the chief parts of the hyoi- 
dean arch, which are also proportionately large in many Siluroids. 
No one, I think, will deny that the structural coincidences here 
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 Accépenser ; and, indeed, 
a still more gristly one, for Accipenser has a large basal ossification. 
The hyomandibular suspensory apparatus must have been equally 
cartilaginous, and, in the vertebral column, only the superior and in- 
