Colorado.' The only other glacier known in this state is the Hallett.2 The Eliot glacier on Mt. Hood, Washington, is retreating and growing thinner (H. D. Langille). This means that the retreat will probably continue for some years and at an increasing rate. On September 3, 1899, an earthquake shook the Alaskan coast and caused a large quantity of ice to be broken from the ends of tide-water glaciers. Glacier bay was so full of ice during the summer of 1900 that the steamers which usually visit that region were unable to approach Muir glacier nearer than four or five miles, and no satisfactory estimates could be made of the retreat of the glacier. The Windom glacier, which ends on gravel-deposits in Taku inlet, is reported to have suffered the loss of a large part of its end, due apparently to the washing out of the supporting gravels. Miles glacier, near the Copper River, Alaska, shows a marked recession since last year (A. C. Spencer). The United States Geological Survey has published a large volume on "Explorations in Alaska in 1898.3 Several parties were sent to explore various routes from the coast to the interior and, although no especial attention was given to the study of the glaciers, sufficient observations were made to bring out some interesting facts; many glaciers are cursorily described and their locations shown on the maps. The Alaskan glaciers are all of the valley or Piedmont types; Alaska was never under a great ice sheet like the eastern part of North America. The glaciers in the mountainous regions to the north, east, and southeast of Cook's Inlet, many of which are very large, were formerly much more extensive than now, and show evidences of continued The Glacier of Mt. Arapahoe, Colorado, WILLIS T. LEE: This JOURNAL, Vol. VIII, pp. 647-654. 2 F. H. CHAPIN: Appalachia, Vol. V. p. 1; and Mountaineering in Colorado, P. 97. 3 Twentieth Ann. Rept. U. S. Geol. Surv., Part VII. See also ABERCROMBIE : The Copper River Exploring Exped. Washington, 1899. retreat. Whereas the glaciers to the west and southwest of Cook's Inlet are small and, though retreating, they were never much larger than at present (Spurr, Mendenhall, Eldridge). Professor I. C. Russell has published an account of the former and present glaciation in northern Washington. A synopsis of the existing glaciers in this region was given in an earlier report of this series." GEOLOGICAL LABORATORY, JOHNS HOPKINS UNIVERSITY, March 15, 1901. HARRY FIELDING REID. 'I. C. RUSSELL: A Preliminary Paper on the Geology of the Cascade Mountains in Northern Washington. Twentieth Ann. Rept. U. S. Geol. Surv., Part II. 2 This JOURNAL, Vol. IV, pp. 222-224. PRODROMITES, A NEW AMMONITE GENUS FROM THE LOWER CARBONIFEROUS CONTENTS Occurrence of Paleozoic Ammonites. Genus: Prodromites Smith and Weller, gen. nov. Prodromites gorbyi (Miller). Prodromites praematurus Smith and Weller, sp. nov. Conclusion. Occurrence of Paleozoic Ammonites.-Until twenty-five years ago it was thought that the ammonites were confined entirely to the Mesozoic, and that the Paleozoic representatives of the Ammonitoid group were all goniatites. This was in keeping with the theory that ammonites all belonged to a single stock or phylum. But the discovery in the Salt Range Permian of several genera of different stocks that could not, by any stretching of the name, be called goniatites, upset this idea. For a long time after this the Permian ammonite fauna of India was looked upon as exceptional until the recognition of the Permian age of the ammonite fauna of the Artinsk beds of Russia. This was followed shortly by the discovery of similar forms in strata of the same age in Sicily and in Texas. It was then universally recognized that these forms were not exceptional, and might be looked for wherever the uppermost Paleozoic was found in its marine facies. But even as late as 1891 we find the Permian ammonite species of Texas described as Mesozoic types occurring in Paleozoic beds, and in all text-books even today the Permian epoch is given as the period of transition from gonia tites into ammonites. Steinmann and von Sutner' were the first to attempt to divide the ammonites into various phyla, derived from separate stocks of goniatites, and while their classification is not always in agreeIment with the most rational arrangement, it is very suggestive, 'STEINMANN: Elemente der Palaeontologie, 1890. 255 and has caused much fruitful discussion. The main points for which they contended have been accepted, and now it is generally admitted that ammonite genera may be much more closely related to goniatites than they are to contemporaneous or even antecedent ammonites. Karpinsky's' masterly researches in the phylogeny of the Prolecanitidæ contributed largely to this result, and prepared the way for Haug's exhaustive study of the relations of the various phyla of goniatites. When it is once admitted that there are several distinct stocks of different degrees of specialization and developing in different directions, there is no longer any sound reason for the commonly accepted opinion that they all made the transition at the same time; indeed, it is extremely illogical to expect that this would be the case. In spite of this, it will cause surprise, especially among those that cling to time-honored criteria, when it is announced that not only are characteristic ammonites found below the Permian, but even at the very base of the Carboniferous system, and in such an advanced stage of development that the transition from goniatite to ammonite must have taken place already in the Devonian. The occurrence of these forms. is authentic, and not sporadic, for they were found in the same horizon, and in the same faunal association in three widely separated localities in America. It may be that they were prematurely specialized forms, like Clymenia, that developed suddenly from the main, unspecialized stock, and as suddenly became extinguished; but the existence of similar and evidently closely related forms in the Trias presupposes continuance of the stock. In reality, our knowledge of the various families of Paleozoic animals is as yet only fragmentary, and lack of record is no very strong argument against the occurrence of any group. We must remember that the greater part of the Paleozoic deposits are not now open to our inspection, and that whole faunal provinces and Die Ammoneen der Artinsk-Stufe. Mém. Acad. Impér. Sci. St. Petersburg, seventh series, Tome XXXVII, No. 2, 1889. 2 Études sur les Goniatites. Mém Soc. Géol. France, Paléontol., Tome VII, No. 18, 1898. regions are now obliterated, either washed away entirely, or covered by the sea, or concealed by later deposits. The first records in the rocks or in text-books do not, by any means, agree with the first appearance of any group in geologic history. This is clearly seen when one notes the constant pushing back of the records of the first appearance of types, that has taken place in the past ten years. Our ideas of the specialization of organic life in Cambrian and even pre-Cambrian time have had to undergo radical changes as the discoveries of new faunas have followed fast upon each other. Genus, Prodromites, gen. nov., Smith and Weller. Type, P. (Goniatites) gorbyi Miller, 1891, Advance Sheets The type species was originally described as a goniatite, but a most liberal interpretation of that group could not include this form, which was assigned to that division simply because of its occurrence in Carboniferous rocks. The genus Prodromites1 is characterized by its laterally compressed, discordal, involute, deeply-embracing whorls, narrow umbilicus, high, hollow abdominal keel, and complex, ceratitic septa. Where the keel is broken off, as is usually the case, the abdomen is narrow, slightly flattened, and angular. The surface, so far as known, is smooth, and destitute of ribs, constrictions, or other ornamentation. The septation is the most distinctive feature of this genus, on account of the large number of serrated lobes, and an extensive auxiliary series of lobes and saddles. The ventral lobe is rather long and undivided, the saddles all rounded and entire, the first four or five lateral lobes are serrated, and in addition to these there is a series of several pointed and more or less irregular auxiliary lobes. The only Paleozoic form to which Prodromites may be likened is Beloceras, which it resembles only in its compressed involute form and the multiplication of the elements of the septa. The resemblance is not great, but the agreement is fundamental, and these two genera may safely be placed in the same family or phylum. A much greater resemblance and probably kinship connects this form with Hedenstroemia Waagen, of the Lower Trias of the oriental region. The best known species of that genus is H. mojsisovicsi Diener, Pal. Indica, Cephalopoda of the Lower Trias, page 63, Plate XX, 'The etymology of the word is from the Greek of scout or forerunner. |