249 ON THE FOSSILIFEROUS LOWER KEUPER ROCKS OF WORCESTERSHIRE, WITH DESCRIPTIONS OF SOME OF THE PLANTS AND ANIMALS DISCOVERED THEREIN. By L. ]. WILLS, B.A., F.G.S., Fellow of King's College, Cambridge. [Read J"ne 4th, [909.] CONTENTS. PAGE INTRODUCTION 249 GEOLOGY- I. Historical Account and Nomenclature 252 2. Description of the Localities 254 3. Lithology of the Lower Keuper • 257 4. The Fossils of the Lower Keuper 264 5. The Area in Lower Keuper Times 266 6. The Age of the Waterstones 268 P ALA;:ONTOLOGY- 1. The Plant Remains . 269 2. Ceratodus cr. Aurri Plien 301 3. Mollusca . 301 4. The Arachnids 302 ApPENDIX On J)ipteronotus cyphus, Egerton, by Dr. A. S. Woodward 322 BIBLIOGRAPHY 323 INTRODUCTION. HE Triassic rocks of Great Britain, if one may judge from T statements in the text-books, are among the simplest of our deposits; but a closer inspection reveals a number of very difficult and intensely interesting problems hidden behind this apparent simplicity. Nor need one go far to discover the reason for this; it is to be found in the fact that the strata are really of a highly specialised nature which has resulted from the "Continental" conditions under which they were laid down. In our ignorance of the laws and factors which govern the formation of shalIow­ water and terrestrial deposits at the present day, we are at once met by serious difficulties in the study of the lithology of a geological formation like the English Trias, which is entirely composed of rocks originating under such conditions. In fact, although we may acknowledge the principles of Uniformitarianism, we cannot at present apply them successfully to such a for­ mation, because the investigation of the correlated present-day phenomena is one of extraordinary difficulty. In studying a geological formation, we are generally able to draw conclusions from an examination both of the lithology and PROC. GEOL. Assoc., VOL. XXI, PART s, 1910.1 19 L. j. WILLS ON T H E FOSSILIFEROUS of the fossil contents. But in the case of the English Trias the almost complete absence, hitherto, of fossils has forced us to base our theories as to its age and origin chiefly on the former characters, the interpretation of which, as has been pointed out, presents exceptional difficulties. Considerable interest, therefore, attaches to the rediscovery a few years ago of a fossiliferous locality in the Lower Keuper Beds at Bromsgrove in Worcestershire. Fossil plant remains had been found there and at other places on the same horizon by the first geological investigators of the area, Murchison and Strick­ land, in {837, but since then the beds have -been practically neglected. In 1907 I published a preliminary account of these deposits in the Geological Magazine, but the amount of material collected has since been considerably increased and has been more thoroughly worked out. Accordingly, I now propose to deal with the results of a detailed study of this material. I have not, however, confined my attention merely to collecting fossils, but I have tried to acquaint myself with the Trias generally in this area, with the object of comparing conclusions derived from both the lithology and the fossils. The study of the fossils has been far from easy, since they include a variety of peculiar forms little known even from the Continental equivalents. The majority are plants whose existence in England has previously been in most cases surmised rather than proved. As, therefore, our museums contained nothing except a few Continental specimens with which comparison could be made, I determined to devote part of a visit to Germany to examining the flora of this format ion as there developed and preserved in various collections. At the same time I visited a number of typical localities showing different horizons in the German Triassic sequence. My sincere thanks are here due to Prof. Rothpletz in Muni ch, Prof. Beckenkamp in Wiirzburg, Prof. Fraas in Stuttgart, Dr. v, Huene at Tiibingen, Prof. Benecke in Strassburg, and Herr Blezinger in Crailsh eim for their cordial help and for the facilities which they accorded me. It is proposed to divide this paper into two parts. The first deal s with the geological aspect of the observations in Worcestershire with the especial object, on the one hand, of investigating the method of deposition of these beds and the physical conditions prevailing in the area at that time ; and on the other hand, of determining the-exact age of the Formation. In both of these endeavours 1- have been helped by the studies made during my visit to Germany, and in both I have, to some extent, been influenced by Dr. v. Huene's suggestive papers on the subject. But my personal acquaintance with the Continental beds has proved of most service as the illus­ trations, if one may use the simile, to Fraas's great work, LOWER KEUPER ROCKS OF WORCESTERSHIRE. 251 Die Bildun~ der germanischen Trias, which enables one to get a clear grasp of the sequence of multitudinous changes that called into being this complex series of rocks. The knowledge gained in Germany has, moreover, enabled me to see my way to a reasonable explanation of the apparently divergent evidence as to the age of the beds, derived from the plant and animal remains respectively. At the same time I am now able to draw a closer lithological comparison with a certain Group in the German sequence than has heretofore been possible. The second part of this paper is devoted to the descrip­ tion of some of the fossils. Of these, the plants merit primary consideration, both because at Bromsgrove they are the most abundant fossils and because they form the first British Triassic flora. For although various plants have been recorded from time to time from the Trias of this country, in nearly every case the state of preservation has proved to be so poor, or the specimens themselves so fragmentary, that no full description or determination could be attempted. In dealing with these remains, my study of the foreign collec­ tions has been of invaluable service; but I must here record my great indebtedness to Mr. Arber for his friendly guidance and criticism, which has contributed in a marked degree to any value which the work may possess. It is claimed that these English plants add considerably to our knowledge of the Triassic representatives of the classes Equisetales, Coniferre, and possibly also Cordaitales. 'Any such contribution is of value, since the flora of the Trias is as yet little known though of considerable importance j for it was during this period and the Permian that the transition from the typical Palseozoic to the typical Mesozoic flora took place. Of the animal remains. the Vertebrates form valuable indices of the age of the beds. They are, however, for the most part in such a fragmentary state as to need the help of specialists, and I have been very fortunate in obtaining the assistance of such authorities as Dr. Smith Woodward and Dr. 1'~. v. Huene in this matter. The former has examined the second known example of the fish Dipteronotus cyphus, Egerton, and confirmed some of my identifications. His notes on Uipteronotus are appended to this paper. Dr. F. v. Huene has recognised among the fragmentary bones .those of Rhynchosaurus and Hyperodapedon. I would like to take this opportunity of expressing my sincere gratitude to both of these gentlemen. The extreme rarity of Mollusca in these beds has led me to describe specimens of a A:fytilus-like shell, which constitutes the only example of this class that has been found in the English Lower Keuper. Arachnidan remains appear to be .one of the characteristic L. ]. WILLS ON THE FOSSILIFEROUS Ieatures of ancient" Continental" rocks. Thus, at the beginning of the" Continental" period, which occurred in Great Britain at the end of Silurian times, we have abundant Eurypterids, while in the Lower Carboniferous Of Scotland and in the Carboniferous and Permian of Bohemia,Scorpions,Thelephonids andPseudoscorpions are among the most interesting members of the fauna. Accord­ ingly, the record and description of Scorpion-like animals from the Trias, which is made here for the first time, may be claimed to be of some importance, especially as they may be considered to be indicative of arid conditions. These arachnids are excep­ tionally well preserved. The chitinous ectoskeleton, which even now retains much of its flexibility, has so far maintained its original state that the sclerites can be extracted from the rock and mounted as transparent microscopic objects. In this they resemble the Eurypterids of the Island of Rootzikull so skilfully developed and described by Holm. Unfortunately they are fragmentary, and no example approaching completeness has been found. The interest of these fossils is rather zoological than geo­ logical. It is, therefore, all the more to be regretted that no complete specimen has been found with which the results of the restoration based on fragments could be compared, for it is more than probable that, in parts at least, it is inaccurate. On the other hand, however, there is much which appears to be indisputable. GEOLOGY. I.-HISTORICAL ACCOUNT AND NOMENCLATURE. In 1837 Murchison and Strickland* presented the first geo­ logical paper on the Triassic rocks of Warwickshire and Worcestershire before the Geological Society. In this they instituted the two large divisions which are known on the Geo­ logical Survey Maps as Lower Keuper Sandstone and Keuper Marls. They were of the opinion, however, that what we now term Lower Keuper Sandstone was equivalent to the German Bunter. This opinion was chiefly based on the identification by Lindley of a cone as Echinostachys ob/ongus, Brongn., a form known from the Bunter of the Vosges, which they held to be sufficient evidence of the age.