Philosophic zoology is yet in its infancy. Extreme conservatism in science fondly rests satisfied with present knowledge, and visionary speculators raise mountains of opinionative systems and theories, which must be cleared away to allow real progress. Between the two classes of operators, the true man of science may have a difficult time of it. Of sawing the air there is abundance, but much as elsewhere very little is done in zoology with due emphasis and discretion. In addition to the species alluded to above, there is found in the forests of Oregon and the Rocky Mountains, the largest of all the Woodpeckers, a magnificent species related to the Ivory-billed Woodpecker of the Southern States, but much larger, and which has up to this period escaped the observation of any American naturalist, except Dr. Townsend, who saw it, but did not procure specimens. It is the _Dryocopus imperialis_, first described by Mr. Gould, a distinguished English ornithologist. This fine bird will be figured in a subsequent part of the present volume. The bird now before the reader was discovered in California by Mr. John G. Bell, of New York, deservedly well known as a naturalist, and beyond comparison the most skilful preparer of birds and quadrupeds and general taxidermist in the United States. Mr. Bell was the first naturalist who visited California after it became a portion of the United States; and during his stay in that country, made a large and highly interesting collection, in which was the present and other new species. He observes in his notes now before us, that he found this bird in one locality only, and observed but two specimens, both of which he obtained. Subsequently this Woodpecker has been found in California by Dr. Heermann, and in New Mexico by Dr. Henry; but is stated by both to be of rare occurrence. The former of these gentlemen observes:— “I procured this bird three years since in the southern mines of California, where it frequents more especially the pine trees. I never saw it alight on the oaks, although abundant in that locality. It is one of the most rare of the Woodpeckers of that country.” Dr. Henry states: “Of this bird I know nothing farther than that I procured a single specimen in the mountains near Fort Webster, in the winter of 1852-3. I shot it from near the summit of a tall pine tree, and was not aware until I obtained it, that it was different from any other species that I had ever seen. My efforts to find it again have been unremitting, but without success; and I regard it as a rare bird in this district. The specimen in my collection is an adult male.” The figure in our plate is two-thirds of the size of life. The plant represented is _Habrothamnus fasciculatus_, a native of Mexico. DESCRIPTION AND TECHNICAL OBSERVATIONS. Genus Melanerpes. Swainson, Fauna Boreali Americana, Birds, p. 316. Melanerpes thyroideus. (Cassin), Proc. Acad. Philada., V., p. 349. (1851.)