Among the fossils discovered by our author, the _Pterichthys_ or winged fish is doubtless the most remarkable. He had disinterred it so early as 1831, but it was only in 1838 that he “introduced it to the acquaintance of geologists.” It was not till 1831 that Mr. Miller began to receive assistance in his studies from without. In the appendix to Messrs. Anderson of Inverness’s admirable _Guide to the Highlands and Islands of Scotland_, which “he perused with intense interest,” he found the most important information respecting the geology of the North of Scotland; and during a correspondence with the accomplished authors of that work, many of his views were developed, and his difficulties removed. In 1838, he communicated to Dr. Malcolmson of Madras, then in Paris, a drawing and description of the _Pterichthys_. His letter was submitted to Agassiz, and subsequently a restored drawing was communicated to the Elgin Scientific Society. The great naturalist, as well as the members of the provincial society, were surprised at the new form of life which Mr. Miller had disclosed, and some of them, no doubt, regarded it with a sceptical eye. “Not many months after, however, a true _bona fide Pterichthys_ was turned up in one of the newly-discovered beds of Nairnshire.” In his last visit to Scotland, Agassiz found six species of the _Pterichthys_, three of which, and the wings of a fourth, were in Mr. Miller’s collection. This remarkable animal has less resemblance than any other fossil of the Old Red Sandstone to anything that now exists. When first brought to view by the single blow of a hammer, there appeared on a ground of light-colored limestone the effigy of a creature, fashioned apparently out of jet, with a body covered with plates, two powerful looking arms articulated at the shoulders, a head as entirely lost in the trunk as that of the ray, (or skate,) and a long angular tail, equal in length to a third of the entire figure. Its general resemblance is to the letter T,—the upper part of the vertical line being swelled out, and the lower part ending in an angular point, the two horizontal portions being, in the opinion of Agassiz, organs of locomotion. To this remarkable fossil M. Agassiz has given the appropriate name of _Pterichthys Milleri_. An account of it, accompanied with two fine specimens, was communicated to the Geological Section of the British Association at Glasgow, in September, 1840; and the most ample details, with accurate drawings, were afterwards published, in 1841, in Mr. Miller’s first work, _The Old Red Sandstone_, which was dedicated to Sir Roderick Murchison, who was born on the Old Red Sandstone of the North, in the same district as Mr. Miller, and whose great acquirements and distinguished labors are known all over the world among scientific men. This admirable work has already passed through three editions. From the originality and accuracy of its