LIFE IN TEFF~.
221
and he bas gathered a good deal of information about its habits. The fishermen here say that this mode of caring dent manner by Heckel and J. Miiller. But, beside these, there are the genem Enoplosus, Pomotis, Centrarehus, and some other neigh boring genera, classed among the Percoids by all Ichthyologists, wltich seem to mc, from this distance and without means of direct comparison, so near the Chromides that I do not see how they can be separated, e~pceially now that I know the lower pharyngials not to be invariably soldered in the Chromides. And then the embryology and metamorphoses of the Chromides, which I have just been studying, have convinced me that the fishes with labyrinthic branch ire, separated from all other fishes by euvier, as a family entirely isolated on account of the strnnge struetme of its respiratory organs, arc closely related to the Chromides. Thus this group becomes, by its various affinities, one of the most interesting of the class of fishe , and the basin of the Amazous seems to be the true home of this family. I will nut fatigue you with my ichthyological researches j let me only add, that the fishes are not uniformly spread over this grcat basin. r have already acquired the certainty that we mu t distinguish sevcral ichthyological faunre very clearly characterized. Thus the species inhabiting the river of Para, from the borders of the sea to the mouth of the Tocantins, differ from those which are met in the network of anastomoses uniting the river of Pani with the Amazons proper. The spccies of the Amazons below the Xingu differ from those which occur higher up; those of the lower course of the Xingu differ from those of the lower course of tbe Tapnjoz. Tbose of the numerous igampes and lakes of !l1:anuos differ us much from tho e of the principal course of the great river and of its great affiuents. It remains now to study the changes which muy take place in this distribution in the eomse of the year, according to the height of tbe waters, and perhaps also aecording to the epoch at which the different species lay tbeir eggs. Thus far I have met but a small number of species huving a very exteusive urea of di~颅 tribution. One of those is the Sudis gigns, found almost everywhere. It is the most important fish of tbe river, that which, as food, cone ponds to cattle for the population along the banks. Another problem to be soh'ed is, how iilr this phcnomenon of the local di tribution of fi hes is repeated in the great affiuents of the Amazons. I shall try to solve it in a cending tbe Rio Negro and Rio Madeira, and as I return to Manuos I shall be oble to compare my first observations in this locality with those of another season of the year. Adieu, my dear fi路iend. Remember me to M. Elie de B aumont and to those of my colleagues of the Academy who are intel'estecl iu my present studies. My kind remembrance also to yonr son. AlwaJ's yours, L. AGASSIZ