[7] I trust that at least by and by there may be an exception claimed, from the general, but, I am sure, well-meant, censure of this passage, in favor of the Free Church of Scotland. It has got as its Professor of Physical Science—thanks to the sagacity of Chalmers—Dr. John Fleming, a man of European reputation, and all that seems further necessary, in order to secure the benefits contemplated in the appointment, is, that attendance on his course should be rendered imperative on _all_ Free Church candidates for the ministry. [8] Agassiz’s description of the _Pterichthys_, as quoted by Humboldt, in his _Cosmos_. [9] From Murchison’s Silurian System. [10] These scales, which occur in a detached state, in a stratified clay of the Old Red Sandstone, near Cromarty, present for their size a larger extent of _cover_ than the scales of any other Ganoid. [11] A peculiarity which also occurs in the anterior dorsal of the _Dipterus_. [12] From the head of _Raja clavata_. [13] The darker, upper patch in this figure indicates a portion in which the scales of the fins in the fossil still retain their enamel;—the lighter, a portion from which the enamel has disappeared. [14] The Acanths of the Coal Measures possess the cranial buckler. [15] Professor Owen, in fixing the homologies of the ichthyic head, differs considerably from Cuvier; but his view seems to be demonstrably the correct one. It will, however, be seen, that in my attempted comparison of the divisions of the ancient ganoid cranium with those of the craniums of existing fishes, the points at issue between the two great naturalists are not involved, otherwise than as mere questions of words. The matter to be determined, for instance, is not whether plate A in the skulls of the cod and _Coccosteus_ be the homologue of a part of the occipital or that of a part of the parietal bones, but whether plate A in the _Coccosteus_ be the homologue of plate A in the cod. The letters employed I have borrowed from Agassiz’s restoration of the _Coccosteus_; whereas the figures intimate divisions which the imperfect keeping of the specimens on which the ichthyologist founded did not enable him to detect. [16] The jaws (10, 10) which exhibit in the print their greatest breadth, would have presented in the animal, seen from beneath, their narrow under-edges, and have nearly fallen into the line of the sub-opercular plates, (13, 13.)