M. Agassiz, in his synoptical table of British fossil fishes, 1843, gives the following list belonging to the Burdiehouse limestone. In the Order of Placoids, _Ichthyodorulites_, there is a Ptychacanthus sublævis, Sphenacanthus serrulatus, and Gyracanthus formosus: of _Cestraciontes_, Otenoptychius pectinatus and denticulatus, and Ctenodus Robertsoni: of _Hybodontes_, Cladodus acutus, parrus, and Hibberti, and Diplodus gibbosus, and minutus. In the Order of Ganoids the following occur: of _Lepidoides_, Palæoniscus ornatissimus, Robisoni, and striolatus, and Eurynotus crenatus, and fimbriatus; of _Sauroids_, Megalichthys Hibberti, Diplopterus Robertsoni, Pygopterus Bucklandi and Jamesoni; of _Cœlacanthes_, Holoptychius Hibberti, sauroides, and striatus, Uronemus lobatus, and a Phyllolepis tenuissimus. Since this list was drawn up, many additional fossils have been obtained from the same locality; some of them exhibit characters which will establish, in all probability, new genera as well as species. The collection in the Edinburgh College Museum contains gigantic specimens in the highest condition of preservation, exciting our wonder at the strange forms which peopled our ancient seas, and admiration of those singular processes by which they have been embalmed by the chemistry of nature, surviving so many changes and disturbances in the history of our planet. The comparative history of the fishes enumerated, in relation to the systems of rocks through which they extend, is both interesting and curious. For example, the genus ptychacanthus begins in the devonian and ends in the carboniferous period, one species peculiar to each formation. Palæoniscus begins in the carboniferous, and continues through the permian age, in five new specific forms. The megalichthys begins in the devonian and becomes extinct in the carboniferous types; diplopterus, holoptychius, and phyllolepis have each the same terms of existence; and again the pygopterus begins in the carboniferous, and survives, in two new species, through the permian era. Thus five genera are common to the devonian and carboniferous systems; two to the carboniferous and permian; eight belong exclusively to and become extinct in the carboniferous. These results clearly manifest an adaptation on the part of nature, as well as some arbitrary principle in the order of her creations, and all speak to the fact of progression in the course of events and of direct interposition in the successive origin of organic existence. Look again into these rocks. Consider the causes which so filled them with these memorials of warfare and death. Two families only, the least predaceous of their kind, survived the age which produced them—one wide revolution covered with its spoils the surface of the earth—the wreck is closed over and silted beneath the waves—and the carboniferous era, teeming with animal and vegetable life, forever passed away.