BUFFALO SOCIETY OF NATURAL SCIENCES 1 57 



The physical and faunal characteristics which have just been de- 

 scribed have usually been interpreted as indicative of shallow- 

 water marine conditions of sedimentation during the late Siluric. 

 The physical nature of the Temeside group would, perhaps, not pre- 

 clude such an origin, but the faunal characters leave no doubt that 

 the Temeside group must have been deposited on the land. As is so 

 frequently the case in such successions of sands and flags, there is 

 no doubt that the material is terrigenous in origin, the only ques- 

 tion being the place of deposition, whether on the land or along the 

 littoral margin of the sea. If we apply the criteria for the recogni- 

 tion of the various types of fossil faunas, it is at once evident that 

 neither throughout the Temeside group nor at any particular hori- 

 zon in it is there a marine fauna, for we have seen that a marine 

 fauna, whether existing under the rather uniform conditions of the 

 open sea or under the more variable environment of the littoral zone, 

 and whether in a sandy, muddy, or pure water facies, was yet made up 

 of diverse classes of organisms with a scattering representation 

 through the phyla of the Invertebrata. In the Temeside group there 

 is no bed containing representatives of more than two invertebrate 

 phyla and usually only one phylum is represented. The maximum 

 thickness of this group is 170 feet. In the lower 50 feet (Down- 

 ton Castle sandstones) the deposits are cross-bedded and contain 

 Lingula minima at certain levels, but no other fossils. Such a series 

 is to be accounted for only by deposition at the mouth of a river, 

 either on the subaerial portion of a delta or on the flood-plain, but the 

 coarseness of the deposits implies that the former was the more 

 probable region of deposition. The presence of beds of Lingulae is 

 easily accounted for by the nature of the shells which are thin, corne- 

 ous, and consequently of small specific gravity. Exceptionally high 

 tides would easily wash in such light shells far up over the delta, while 

 heavier shells would be dropped farther out in the littoral waters. It 

 is evident that the Lingulae must have been transported from their 

 original habitat since they are unassociated with any other forms 

 of life, unless they can be regarded as living in the river mouths. 

 Thus the assortment seems to have been by specific gravity. In the 

 120 feet of the Temeside group, Lingula cornea replaces L. minima 

 in the single bands, and is to be accounted for in a similar manner. 

 Now it might be suggested that the eurypterids, which are likewise 

 found in thin bands, were also washed in from the sea on account of 

 their light specific gravity; but the difference between the two cases 



