The Scapular Arch and Fore Limbs.—The scapula is massive, especially below. The shaft is long and narrow, with a thin edge in front, and a thick posterior margin above the glenoid fossa. The distal portion has a median external ridge, and a thick end (Woodcut, p. 242, Fig. 1, sc.).

In previous numbers of this Magazine, the writer has given the principal characters of the gigantic Ceratopsidœ, or horned Dinosaurs, from the Laramie, with figures of the more important parts of the skull and skeleton. The abundant material now available for examination makes it possible to attempt a restoration of one characteristic form, and the result is given in Plate VII. This figure, about one-fortieth of natural size, is reduced from a large outline plate of a memoir on this group, now in preparation by the writer for the United States Geological Survey.

The Tonga or Friendly Islands in the South Pacific Ocean seem to have received hitherto no attention from geologists, and I can find no published information as to their geological constitution beyond the simple record of the existence of volcanoes and coral-reefs. The material of these brief notes was mostly collected by Mr. J. J. Lister, M.A., during the cruise of H.M.S. Egeria in 1889; and, through the courtesy of Captain Wharton, R.N., F.R.S., Hydrographer to the Admiralty, I have had the opportunity of examining a few additional specimens collected by Captain C. F. Oldham, R.N., Commander of the Egeria, in 1890. In view of the general account of the islands which Mr. Lister is preparing, I notice here only such points as arise directly from an examination of the specimens.

As a sequel to my recent paper on new specimens of Dendrerpeton, I have thought it desirable to reproduce by photogravure, for comparison, the type specimen of Hylonomus Lyelli now in the collection of the Geological Society of London. The reproduction (Plate VIII.) is of the natural size, though less distinct than in the original. Though the bones are scattered, this specimen enabled me, by measuring the separate bones and adding the cuticular scales found on other specimens, to restore the animal in my “Airbreathers of the Coal Period.”

Mr. W. M. Hutchings' “Notes on the Fireclays of the Coalmeasures,” published in the April Number of the Geol. Mag., contains many interesting facts and suggestions on which I should like to offer a few remarks.

The growing interest in the evolution of the Continent now calls for more accurate information than formerly regarding the changes of level of land and sea in recent geological times. The amount of these oscillations was one of the most important factors in the investigation of the “Building of the Great Lakes.” Hence the study of the history of the lakes has contributed to our knowledge of the changing relations of the continent and the sea.

My letter in the March Number of the Geological Magazine, asking for a description of the “Herschel-Babbage” theory of Mountain formation, appears to have called forth Mr. Davison's “Note on the Expansion Theory of Mountain Evolution,” in which he favours us with his definition of the “fundamental principle of the theory of terrestrial evolution which has sometimes been called the ‘expansion theory.’”

The high price of all heavy liquids, and the consequent care that has to be taken in using them, the latter of course entailing great expenditure of time, were the reasons which caused me to make experiments, with regard to the manufacture of Klein's solution (borotungstate of cadmium) on a small scale. The price quoted in a well-known chemical manufacturer's price-list is 3s. 6d. per oz. My experiments have shown me that it can be made for about 7d. per oz., plus the value of the time of the maker. The process is very simple, and not much time is necessary in making it. A rough outline of the method of preparation is given by Dr. Klein in the Comptes Rendus, vol. xciii. August, 1881.