They feed as far as they are known, on Monocotyledoneous plants, the extra-tropical ones, with one exception perhaps, exclusively on Graminaceous plants. The Caterpillars shun the sunlight and hide themselves in the grass. Some of them bury themselves in the daytime in the ground and feed only at night. The tropical species feeding on Scitaminaceous, Aroideous plants, palms, and arborescent grasses, sport the shady thickets of tropical forests, in whose twilight depths, most of the species are also found in their imago state. Other ones like some of the Morphonides, and even some Nymphalides of the tropics, spend their days hidden under the luxuriant foliage of primeval forests and begin their flight only after sunset.
In a most interesting treatise on the characteristics of the insect fauna of the “White Mountains,” by Samuel H. Scudder, (Boston Journal, Vol. VII, Part IV), I find the description of the Caterpillar of Chionobas Semidea, Edw., with a notice that it was found on Lichen. This would prove a most remarkable exception, as all the other Satyrides feed on Monocotyledoneous plants. Nevertheless, larvæ of Artic types are generally polyphagous, and adapted to some degree, to accommodate themselves to circumstances, and so I would not entertain any doubts about the feeding plant of the Chionobas, if it were not for the circumstance that Mr. Scudder confesses that he did not succeed in bringing the Caterpillar, with Lichen, to perfection. Perhaps the Caterpillar fed on grass, or perhaps some Carex, and was only, by some accident, compelled to crawl to the lichen-covered stone, where that gentleman found it. I hope to hear very soon about this most interesting object, for I consider the discovery of the metamorphoses of one insect, a more valuable fact than the diagnoses of ten new species, of which we do not know more than the external appearance.
Prof. Wm. P. Blake presented the following papers:
Note on a large lump of Gold found on the Middle fork of the American River.
BY PROF. WM. P. BLAKE.
In July last, a mass of gold nearly free from quartz, was taken out of a placer on the Middle Fork of the American River, about two miles above Michegan Bluffs. It weighed, as taken out, 187 ounces troy, and sold for $17.50 per ounce, netting the finder $3,272.50. In melting, a loss of six ounces was experienced. There was a further loss to the purchaser, from the poor quality of the gold, the assay return of which I have not yet been able to obtain. The ordinary gold of the claim is worth $17.50. It is a singular fact, often remarked by dealers, that the large lumps of gold are almost always poorer in quality than the smaller ordinary grains from the same placers.
Note on the Fossil remains of the Horse and Elephant, mingled, at Mare Island, San Francisco Bay.
BY PROF. WM. P. BLAKE.
The entire lower jaw and teeth of a horse, the fragments of which I exhibit to the Academy, were taken by me from the face of the shore cliff of Mare Island, together with broken pieces of bones of other large quadrupeds. The teeth of an Elephas had been found in the same place, a few weeks before, by Mr. Brown, the Naval Engineer, by whom my attention was directed to the place. The fossils occur in a stiff sandy loam, which rests on the eroded surface of the Tertiary or Cretaceous beds below. Near the surface is a layer of oyster shells, apparently an upraised bed, most of the shells being entire. The fact that the Horse and Elephant roamed together over our hills and plains, at the dawn of, or before the human period, is certainly not without interest.