for engines working with intermissions and during brief spaces of time, the property of liquid carbonic acid, of being always ready for work, is of much importance. By this same property, and since the mechanical equivalent of electricity is very small, such au engine is a very fit and cheap source of electrical light. My method of compression furnishes easily the required tension for the conveyance of letters in tubes, and the modern break-apparatus for railways." Further, the author suggests that his discovery might be turned to account in artillery, and in the construction of submarine vessels.
New Eocene Mammals.—Prof. Marsh is now contributing to the American Journal of Science a series of notices on new and hitherto undescribed mammals found in the Tertiary strata of the West. In the March number of the Journal he describes some new forms of quadrumana, a species of his new order Tillodontia, three species of rhinoceros, a new species of Brontotherium, and various other extinct animal forms. Among the quadrumana here described, we have a new genus, Lemuravus, closely resembling the lemurs in skeleton and in the general structure of the skull. The species L. distans was about the size of the largest squirrels. During the late raid into the "Bad Lands" of Nebraska, Prof. Marsh found the lower jaw of a monkey, which indicated an animal about the size of a coati; it is the first specimen of the order Primates found in that region, and forms a new genus and species—Laopithecus robustus. The order Tillodontia is represented by the new species Tillotherium fodiens. The animals of this order are among the most remarkable yet discovered in American strata. They seem to combine characters of several distinct groups, viz., carnivores, ungulates, and rodents. The Tillotherium fodiens would appear to have been about two-thirds as large as a tapir. The rhinoceroses described are Diceratherium armatum, D. nannum, and D. advenum. These animals had a pair of horns placed transversely, as in modern ruminants,-as is clearly indicated by large, bony protuberances on the anterior portion of the nasal bones. The D. armatum, would appear to have been about two-thirds as large as the Indian rhinoceros; the D. nanum was scarcely more than half the bulk of the preceding; while the D. advenum was half the bulk of the Indian rhinoceros. The new genus of Brontotheridæ is denominated Anisacodon, and it is represented by the new species A. montanus. According to the author, this family consists of four well-marked genera, viz., titanotherium, megacerops, brontotherium, and anisacodon. The name Diplacodon elatus is given to a new genus and species intermediate between Limnohyus and Brontotherium. Two new equine species from the Miocene are described, and three new species allied to the collared peccary.
Premature Criticism.—Mr. Proctor, in the English Mechanic, calls attention to a very curious piece of literary criticism occurring, of all places in the world, in the Atlantic Monthly. The critic is very severe in his sentence upon "The Sun," "The Orbs around Us," and other works by Mr. Proctor, but the value of his judgment is impaired by the evidence Mr. Proctor furnishes to show that it is not based on a knowledge of what is contained in the books. Among the works thus adversely criticised is "Other Suns than Ours." Of this Mr. Proctor says: "It may be as bad as he says; it may be 'trash,' and it may 'confirm the evil prognostic of its title,' but he might have waited till it was published. Three years ago, when it was half written, it was announced for early publication. Unfortunately for my critic (but fortunately for me), he has been led to suppose that the work accordingly appeared, and might safely be abused. But a great pressure of work prevented me from completing some stellar observations necessary for its illustration, and the MS. still lies unfinished in my desk. What a savage literary Herod a man must be who would thus slaughter the book unborn!"
Fossils in Trap-Rock.—The occurrence of fossils in trap-rock, though not uncommon, still awaits a satisfactory explanation. Mr. E. A. Wünsch, writing in a late number of Nature, mentions several instances of the presence of both plant and animal remains
