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Page:Popular Science Monthly Volume 4.djvu/630

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THE POPULAR SCIENCE MONTHLY.

to discard barbarous names, and, when a species becomes the type of a new genus, he would retain the former specific name as the generic appellative. He objects to the use of small initial letters for substantives borrowed from persons or places, to the uniform restriction of family and sub-family terminations to idœ and inœ, and strongly condemns the proposition that the name of the original propounder of a species should be retained when the species is transferred to a different genus. He likewise condemns those who would change the authority for a genus when the name is changed through faulty orthography, and censures the use of vernacular names in scientific works to the exclusion of the systematic ones.

The "Fossil Fishes" was now approaching completion, but, in consequence of additional material, Agassiz determined to publish a supplement; and accordingly there appeared, in 1844, the "Fossil Fishes of the Old Red Sandstone." It was accompanied by an atlas of thirty-nine folio plates illustrative of the seventy-six species described. The author, after discussing the relative rank of the members of the various classes of the animal kingdom, and showing how closely the time of their appearance on the earth corresponds to their relative standing in their respective classes, announces the conclusions to which a study of the fishes of the Devonian system had led him. These fishes actually represent the embryonic age of the Reign of Fishes, undergoing "phases of development analogous to those of the embryo, and similar to the gradations which the present creation shows us in the ascending series it presents when viewed as a whole." The members of the five families whose species he describes, are characterized by the absence of distinct vertebræ, the apophyses resting on the spinal cord, and by the absence of ossification in the internal case of the cranium. In these characters, as well as in the peculiar development of the vertical fins, the heterocercal tail, the flattened form of the head, and inferior or sub-inferior mouth, we see peculiarities of structure common to the embryo and the lower forms of existing as well as paleozoic fishes. This affords us a key to the relative rank of these fishes, for we find the Cephalaspides, which recede most from the existing forms, confined to the Devonian. The Sauroids, which are represented only by a particular group—the Dipterians—are likewise confined to the Devonian. The Acanthodians become extinct at the end of the Chalk, while the Cestraciontes persist to the present epoch. The same year Agassiz also read before the British Association a "Report on the Fossil Fishes of the London Clay."

Of all Agassiz's investigations, perhaps none made his name more popularly known than his studies on glaciers—studies which were pursued through a long course of years, and conducted with the same painstaking care that had heretofore characterized all his labors.

About the year 1834, M. Charpentier advanced the theory that the erratic blocks, and certain dikes of peculiar shape found in the