There can be no doubt that the name Megalichthys was originally suggested to Agassiz by the gigantic teeth of the great round-scaled fish first brought into notice by the researches of Dr. Hibbert, in the quarries of Burdiehouse, though indeed some of its remains had long previously been figured by Ure in his “History of Rutherglen and East Kilbride.” Incontrovertible evidence of this may be found by referring to the Proceedings of the British Association for 1834, and to Dr. Hibbert's original memoir on the Burdiehouse Limestone published in the Transactions of the Royal Society of Edinburgh, vol. xiii. 1835. But with the remains of this enormous creature were also associated and confounded certain rhombic glistening scales, belonging really to a considerably smaller fish of a totally different genus, and when Agassiz, subsequently to the meeting of the British Association at Edinburgh in the year above quoted, found in the Museum at Leeds a head of this latter form, or at least of an allied species, he adopted it, by description and by figure, as the type of his Megalichthys Hibberti, relegating the other to the genus Holoptychius. This latter, the real “big fish,” is now known as Rhizodus Hibberti, the founder of the genus being Prof. Owen; and though it may be a matter of regret that it did not retain the name Megalichthys, the laws of zoological nomenclature do not admit of any alteration now.