INTRODUCTION. At the meeting of the British Association, held at Edinburgh in 1834, Dr. Hibbert read a paper before the Geological Section on a series of fossil remains found in the Burdiehouse limestone, near Edinburgh. These contained a series of fish remains, among which, besides Gyracanthus, Palaeoniscus, Erynotus, Pygopterus, were some bones, scales, and teeth, remarkable for their great size, and also some smaller rhombic enamelled scales.* Prof. Agassiz being present the remains were submitted to him for his opinion. They proving new and strange to him, he, Drs. Hibbert and Buckland formed a committee to report on them. About this time Agassiz, whilst on a visit to Leeds, saw in the Museum there a fine and well-preserved head and part of the trunk of a fish, which he seems to have considered of the same species as the Burdiehouse remains. This new find having relieved his doubts concerning the Burdiehouse fish, he took the Leeds specimen as the type of his genus Megalichthys, and at that time included the large rounded scales and gigantic teeth, as well as the smaller rhombic enamelled scales, in this genus. Later, however, he separated the large rounded scales and the teeth, placing them in a new genus Holoptychius. † It is very unfortunate that Agassiz made the Leeds fish his type, as undoubtedly the name Megalichthys was suggested to him by the great size of the Burdiehouse remains, for which in 1840* Prof. Owen instituted the genus Rhizodus. Systematic Position.—Agassiz classed Megalichthys in ...