304 PROCf^.EDINGS OF UNITED STATES NATIONAL MUSEUM. [1885. America, 18G9, 397). Dr. Gilnther assumes that nearly one-third of the total number of species of marine fishes on the two shores of tropical America will be found to be identical. Hence he infers that there must have been, at a comparatively recent date, a depression of the isthmus, producing an intermingling of the tsvo faunjie. This discrepancy arises from the comparatively limited representa-tion of the two faunae at the disposal of Dr. Giinther. He enumerates 19o marine or brackish-water species, as found on the two coasts, 59 of which are regarded by him as specifically identical — this being 31 per cent, of the whole. But in 30 of these 59 cases I regard the assump-tion of complete identity as erroneous, so that taliing the number 193, as given, I would reduce the percentage to 15. But these 193 species form but a fragment of the total fauna, and any conclusions based on such narrow data are certain to be misleading. Of the 71 identical species admitted in our list, several (e. </., Mola, Or-cynus) are pelagic fishes common to most warm seas. Still others (c. ^., Trachurus, Caranx^ Diodon, sp.) are almost cosmopolitan in the tropical waters. Most of the others {e. </., Gobins, Gerres, Centropomus, Ga-leichthys sp., &c.) often ascend the rivers of the tropics, and we may account for their ditfusion jjerhaps, as we account for the dispersion of fresh-water fishes on the isthmus, on the supposition that they may have crossed from marsh to marsh at some time in the rainy season. In very few cases are representatives of any species from opposite sides of the isthmus exactly alike in all respects. These difi"erences in some cases seem worthy of 'specific value, giving us ''representative species," on the two sides. In other cases, the distinctions are very trivial, but in most cases, they are appreciable, especially on fresh speci-mens. I am therefore brought to the conclusion that the fish faunae of the two shores of Central America are substantially distinct, so far as species are concerned, and that the resemblance between them is not so great as to necessitate the hypothesis of the recent existence of a channel across the isthmus, j^ermitting the fishes to pass from one side to the other. Indiana University, J»?j/ 18, 1885. NOTE ON SOME LINNiEAN NAMES OF AMERICAN FISHES. By DAVID !><. JORDAN. In the current volume of these Proceedings (pj). 193-208) is a very useful "contribution to the stability of American ichthyological no-menclature," entitled "On the Americnn Fishes in the Linnaean Collec-tion," by Messrs. Goode and Bean. Most of the changes suggested in this pai)er are well founded, and some of them have already been adopted by the writer from verbal statements of Dr. Bean, A few seem to need further discussion.
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