104 NEW YORK STATE MUSEUM 



recorded up to that time were brought together, and these with 

 other later obseryations indicate that the fossil is not diffused 

 generally throughout the Old Ked strata but in its profuse mani- 

 festation at least is somewhat localized. Hugh Miller figured 

 the species in various editions of the Old Red sandstone and Cruise 

 of the Betsey, from the flagstones and shales of Caithness, and he 

 was also among the earliest to record its occurrence on the islands 

 of Orkney and Shetland. The position of the Estheria beds or 

 Caithness shales on Orkney is stated by Prof. Jones (p. 17), quot- 

 ing John Miller of Thurso, to be the middle beds of the Old Red 

 sandstone, according to the subdivision of that series as made out 

 by Sedgwick" and Murchison, where the fossil is associated with 

 a profusion of fish remains but with no other organism, so far 

 as the records show. As to the proper interpretation of the ex- 

 tensive masses of Old Red sandstone deposits representing al- 

 together local manifestation of sedimentation of Upper Siluric 

 and Devonic data, probably even continuing into early Carbonic 

 time, Sir Archibald Geikie speaks with fullest authority. In 

 view of the significance which may attach to the appearance of 

 Estheria membranacea in Kew YoTk in intimate associ- 

 ation with sediments of the same order as the tj^ical Old Red 

 sandstone, it will be serviceable to here cite the opinions of the 

 former director of the geologic survey of the United Kingdom.^ 



The Old Red sandstone of Britain, according to the author's 

 researches, consists of the following subdivisions. 



2 Upper. Yellow and red sandstones, conglomerates, marls 

 etc., passing up comformably into the base of the Carboniferous 

 system and resting unconformably on the Lower Old Red sand- 

 stone and every older formation — H oloptychius^Pterich- 

 t h y s major, etc. 



1 Lower. Red sandstones, conglomerates, flagstones and as- 

 sociated igneous rocks, passing in some places conformably down 

 into Upper Silurian formations — D ipterus, Coccosteus, 

 Cephalaspis, Pterygotus, etc. 



Sir Archibald Geikie, regarding these geographically distinct 

 masses of sediments as having been deposited in isolated lake 



^Textbook of geology. 18S2. p. 712 et seq. 



