MONOPTERUS GIGAS. A. new genus, established on a very bad specimen of a fossil fish, which Bloch thinks to be rather a cyprinus. That our ichthyological readers may judge what reliance is to he placed on these new gene ra and species, in which M. Blainville's work abounds, respecting which we gave a hint already, we shall give, as a specimen, the description of this fossil ; though very far from being the most imperfect of those that have come under our examination. " The fragment in question is about a foot long, and half a foot broad. The head, which appears to have been short and truncated, is continuous on its upper outline with the back, which is very much arch ed, and covered with some slight marks of small scales. There are no indications of eyes, nor of opercula, nor of the pectoral or abdominal fins ; and there is one dorsal fin, placed rather far back, rounded, and of moderate size.
This, together with the anal one, which is opposed to it, seems to be formed of soft rays, and the latter appears to have been notched behind; while the foremost rays are the longest, and the first of all is very strong and thick, and as if it was grooved transversely. The caudal fin is remarkable for the length and narrowness of its lobes, and for a deep notch ; while it lies behind a long conical pelli cle. There is the ray of a fin, which appears as if it issued from the mouth, and which it is suppcsed, might have be longed to the abdominal fin." As we have been obliged to have recourse to this work as the most recent and most esteemed on the subject of fossil fish, it is a duty we owe our readers to let them see, as far as we can, on what kind of grounds these new ar rangements stand.