_V. Californica_ is remarkable from its being one of the few wandering Lepidoptera yet known. The first migration I observed was on November 15th, 1856, when numbers of this butterfly flew over San Francisco in a general direction of south-south-east. They flew singly, and never crowded into swarms. Most of these butterflies passed over our streets at too great a height to permit close inspection—a few alighting here and there on lamp-posts, sign-boards, or in the more rural parts, on flowers. It was from these that I obtained the specimens in my collection. They nearly all looked worn and shattered, and there were no fresh specimens among them: clearly indicating that they were not raised in the neighborhood of the city, but had come from distant parts. On the 18th some of the stragglers were still to be seen, but on the 19th they had all disappeared. The second migration took place last fall, but did not reach San Francisco. I received a series of specimens, caught by Dr. Cooper, on the road to Lake Taho. Others I received from Oregon, where they were collected by Mr. Gabb, during his geological examination of those northern regions. Neither Dr. Cooper nor Mr. Gabb observed any marked direction in the flight of these butterflies; they agree that the species was strikingly numerous. Mr. Gabb represents it as settling on the ground in dry arroyos, very shy, and when frightened, always returning to the same spot—a behavior which pretty nearly corresponds with that of the nearest relative, the European _V. Polychloros_. Both of these authorities prove merely an unusual number of this butterfly at an unusual time of the year. The description of the habits of the insect, as observed by Mr. Gabb in the Umpqua Valley, show clearly that there it felt at home. By comparing notes received from Mr. Johnson, of Marin County, I have come to the conclusion that the country to the northward, crowded with this Vanessa, must have sent at least one colony south; and I was told by the above-mentioned gentleman, the statement being confirmed by several intelligent farmers of the same neighborhood, that large numbers of a brown butterfly had come from San Quentin, and crossed over that part of the bay which stretches between San Rafael and Saucelito. About the same time, great numbers of the same insect were observed in Lagunita Valley, at the base of Tamal Pais, where the swarms gathered in a great crowd, and disappeared as suddenly as they came.