Whilst working at the fossils connected with our paper “A Study of Ballstone and the Associated Beds in theWenlock Limestone of Shropshire”, my colleague, Miss M. C.Crosfield, and I became much interested in a small round form of Labechia. We did not find many specimens, about a dozen in all,although we spent a considerable time in collecting, and these wereobtained at only three quarries, which contain otherwise a prolificfauna, viz. Bradley Rock and Shadwell Rock, Much Wenlock, andat Knole Quarry, Presthope. The tops of these quarries are in thehighest beds of the Wenlock Limestone series and are of bands ofirregularly shaped nodules of various sizes, with shale partings andof a light-brown colour (this latter fact distinguishes the beds fromthe rest of the limestone). It is only in these upper beds that this Labechia is found, but Labechia conferta, Lonsd., is found, often in greatnumbers and size, everywhere throughout the limestone, thoughperhaps slightly diminishing in quantity at the top. So far, I havenot been able satisfactorily to identify this species. Nicholson, in his monograph, mentions and figures a young example of L. conferta, which he records as only being 2 to 3 cm. in diameter and 1 mm. inthickness.

After the little survey of the pluvial epoch contained in thepreceding section we may turn our attention again to England.In the Thames Valley at Swanscombe (Barnfield pit) there is foundbeneath the deposits which yield early Chellean implements a yetolder layer which does not contain any implements.

In the description of the skeleton of Metriorhynchus given in vol. ii of the Catalogue of the Marine Reptiles of the Oxford Clay, very little could be said about the fore-limb. The only partsthen known were a number of humeri and, in one or two cases, somesmall disc-like bones which were regarded as the radius and ulna:the most complete fore-limb was figured on p. 172 of the volumequoted. In order in some degree to fill this gap a short account wasgiven (torn, cit., Introduction, p. xiii) of an imperfect fore-paddle ofa specimen of the closely related Geosaurus graeilis from the Solenhofenlimestone. This beautiful skeleton, originally described by V. Ammon(Geognostische Jahreshefte, vol. xviii, p. 12), has recently beenacquired by the British Museum, and a photograph of it is given asa frontispiece to vol. ii of the Catalogue of Oxford Clay Reptiles. The specimen is beautifully preserved, and is remarkable for showingthe outline of the tail-fin and other traces of the soft parts.

The relation of the Torridon Sandstone to the Moine Gneiss or ‘Eastern Schists’ is one of the primary questions in thegeology of the Scottish Highlands. These two widespread series ofrocks occur on opposite sides of the great overthrusts in North-Western Scotland; and another remarkable feature of their distributionis that though the Torridon Sandstone often rests directly upon theLewisian Gneiss, it never occurs on the Moine Gneiss. The view hastherefore been suggested that the Moine rocks are the easternmetamorphosed continuation of the Torridonian. Some altered Torridon Sandstones certainly resemble the rocks of the Moine Series.Dr. Home, in his address to the British Association in 1901, quotedthe authority of Dr. Teall and Dr. Peach for the resemblance ofaltered Torridon Sandstone to the Moine; and he again remarked thisresemblance in the memoir on the North-West Highlands. The lateW. Gunn went further, and in the same work claimed (p. 612) that “east of Dundonnell good evidence can be adduced that alteredTorridon Sandstone has entered largely into the composition of the Eastern schists”. The recent memoir on the Fannich Mountains represents some of the flaggy granulites of that district as due “to the crushing of Torridonn grit”.

Perhaps one of the most unexpected facts concerning the geology of the Polar regions is the almost entire absence of pre-Quaternaryrocks composed of glacial detritus, and the presence there mainly ofsediments containing floras and faunas indicating warm climaticconditions. This is true of the rocks composing the AntarcticContinent as well as of the land masses in the neighbourhood of theArctic Sea. Indeed, it is not until rocks of late Tertiary or Quaternarytimes are reached that we get any signs of continuous frigid conditionsat the Poles.

Although the so-called Crawfordjohn essexite has been mentioned several times in petrographic literature, no detailed description of the occurrence has been given. In 1888 Teall described the main rock of the intrusion as an abnormal variety ofthe N. W.-S.E. Kainozoic dykes and noted the porphyritic augite andthe abundance of felspar, olivine, and apatite. Lacroix, in a generalpaper on the teschenites, mentioned the occurrence of nephelite in the same rock, which he described as an “olivine-teschenite, passing instructure to a tephrite”. Bailey, in the Glasgow memoir, remarked on the close similarity between the Crawfordjohn and Lennoxtown rocks and classed them with the essexites on account of their chemical similarity to the Brandberget rocks, while Tyrrell, on account ofthis similarity and also of the resemblance to the Carclout essexite, included them in the late Palaeozoic alkaline group.

The subfamilies Thecidiinæ, Dall, and Leptodinæ, Schuchert, constitute the family Thecidiidæ, Gray, which is regarded by Schuchert as a near relation of the Strophomenidæ. The chief external characters of the Thecidiinæ are the smallness of the shells, the absence of the foramen, attachment by the ventral valve, the presence of a nearly straight hinge-line and of a prominent area with a solid deltidium. The shell substance, with the exception of the deltidium, is punctate. Internally the ventral valve bears in its hollow beak a small edian septum on which is sometimes superposed a small muscular plate. The dorsal valve bears a so-called cardinal process, formed by the median union of the socket ridges, and this plate is strong, subrectangular, and hollow at its base, and projects beyond the hinge. In most of the genera two lateral spurs unite mesially to form a bridge just in front of the cardinal process, over the visceral cavity. There are no free brachial arms, but the brachial supports are represented by an anterior septum, frequently branched, and lamellae rising from the floor of the valve in the spaces between the septum and its branches, the margins, and the bridge. The septum runs back from the anterior margin towards the bridge, and like the margins and the bridge, is more or less covered with granulations.