TUE ASTEROLEPIS, 



It is on this inner side of the cranial buckler, where there 

 are no such pseudo-joinings indicated as on the external sur- 

 face, that the homologies of the plates of which it is composed 

 can be best traced. It might be well, however, ere setting 

 one's self to the work of comparison, to examine the skulls 

 of a few of the osseous fishes of our coasts, and to mark how 

 very considerably they differ from one another in their lines 

 of suture and their general form. The cerebral divisions of 

 the conger-eel, for instance, are very unlike those of the had- 

 dock or whiting ; and the sutures in the head of the gurnard 

 are dissimilarly arranged from those in the head of the perch. 

 And after tracing the general type in the more anomalous 

 forms, and finding, with Cuvier, that in even these the " skull 

 consists of the same bones, though much subdivided, as the 

 skulls of the other vertebrata," we will be the better qualified 

 for grappling with the not greater anomalies which occur in 

 the cranial buckler of the Asterolepis. The occipital plate, 

 Fig. 31. 



PLATES OF CKANIAL BUCKLER OF ASTEROLEPIS. 



Af a, a (fig. 31), occupies its ordinary place opposite the 

 centre of the nape ; the two parietals, B, B, rest beside it ia 



