AMNIGENIA AND FRESH-WATER DEPOSITS 201 



The Old Red sandstone attains a great development in the 

 south and southwest of Ireland. The thick " Dingle beds " and 

 " Glengarin' grits " pass down into Upper Silurian strata, and 

 no doubt represent the Lower Old Red sandstones which cover 

 them un conformably and resemble the ordinary Upper Old Red 

 sandstone of Scotland. In Cork and the southeast of Ireland 

 they are followed by the pale sandstones and shaly flagstones 

 known as the " Kiltorcan beds ", with apparently a perfect con- 

 formability. The Kiltorcan beds (which pass up conformably 

 into the Carboniferous slate) have yielded a few fishes (JBoth- 

 riolepsis, Coecosteus, Ptericthys, Glyptolepis), some crustaceans 

 (Belinurus, Pterygotus), a fresh-water lamellibranch (A n o - 

 d o n t a j u k e s i), and a number of ferns and other land plants 

 (Palaeopteris, Sphenopteris, Sagenaria (Cyclostigma), Knorria). 



The occurrence of A. j u k e s i is thus parallel in character 

 and age to that of A. c a t s k i 1 1 e n s i s . 



Beuishausen describes 1 as Amnigenia r h e n ana, a shell 

 of about the size and proportions of A. c a t s k i 1 1 e n s i s from 

 various localities in the vicinity of Grafrath in the Rhine prov- 

 ince. The precise stratigraphic position of this species is not 

 clearly established by the author cited, but from collateral evi- 

 dence is regarded as probably of late middle Devonic age. The 

 only fossils associated with it in the sandstone beds where it 

 occurs are fragments of plants which are scarcely capable of 

 identification. " This association with plant remains, as well as 

 the character of the whole succession of sediments, doubtless indi- 

 cates a near coast line, and one will not go far astray in con 

 eluding from the contemporaneous absence of all traces of a 

 marine fauna, that these sediments are probably brackish water 

 deposits ". 2 



The Oneonta-Catskill sedimentation in its fullest development 

 doubtless represents time from at least the close of the Hamilton 

 stage. Prof. Hall was disposed in some of his writings? to regard 

 the upper part of the Hamilton series of strata, as developed in 

 central New York, as replaced eastward by the Oneonta beds. 

 Present evidence may not fully corroborate this interpretation, 



i Jahrb. d. konig. preuss. geol. Laudesanstalt f iir 1890. separat p. 1-10, 1891. 



a Idem. p. 2. 



a See specially Pal. N. Y. v. 5, pt 1, 2, p. 517. 



