I am indebted to Mr. Titian R. Peale for the use of the original from which our model was taken, his liberality to those who cultivate Natural History is proverbial, and needs no encomium from me. The C. Microps is said to have been found near Ripley, Ohio. It occurs in black limestone. The eyes of this Calymene are small in comparison with those of some other species--particularly the C. Bufo, C. Macrophthalma, and C. Anchiops. Calymene Anchiops.[18] _Green._ Cast No. 7. [Footnote 18: From two Greek words which signify "eyes approximate."] Clypeo antice, caudaque postice rotundatis; oculis approximis, magnis, excertis; articulis vigenti; corpore plano. The buckler of this species is irregularly hemispherical; the front pyriform and without pustulations. The cheeks are almost entirely occupied by the eyes, which are placed very near each other on the upper part of the forehead; are very large and trilobate, the side lobes being elongated and attenuated in front. The articulations of the back are twenty in number, those of the abdomen not being distinguishable from those of the tail. The costal arches of the side lobes are round near their extremities, and are intersected with two or three raised lines. Length nearly four inches. Breadth about two inches. It gives me great satisfaction in being able to describe, and to present to naturalists a good cast of this Calymene, which has excited for a long time so much interest and perplexity. The original fossil from which our plaster model was made is now deposited in the cabinet of the Albany Institute, and is the identical specimen from which a cast was long since made, by Dr. Hosack of New York, a specimen of which he sent in July, 1819, to the Royal Academy of Science, in France. Professor Brongniart referred the animal from which this model was taken, though with much hesitation and doubt, to the species, Calymene Macrophthalma. He remarks concerning it, "Il est beaucoup plus gros que les autres individus, et a prés de dneuf centimètres de longueur. C'est avec doute que je rapporté cette empreinte tres-peu nette à l'espèce actuelle; mais malgré ses formés obtuses, et l'absence de tout detail, elle est si remarquable par la grosseur de ces yeux et par le prolongement de son bouclier qu'on peut présumer qu'elle appartient an calyméne macrophthalme, et avec d'autànt plus de probabilité qu'elle vient aussi des Etats Unis d'Amérique. Elle a été trouvée, suivant M. Hosack, dans un schiste." We have seen the cast alluded to in the above note, and are not at all surprised at the uncertainty which it has occasioned. The apparent prolongation of the buckler is entirely occasioned by the loss of a small fragment from that portion of the head. The form and position of the eyes, further distinguish it from any of the numerous specimens of C. Macrophthalma, that we have examined. The raised lines which we have noticed as intersecting the costal arches of the lateral lobes