42 FOSSIL ESTHERItE. 



In both of the foregoing extracts this red sandstone is treated of as Triassic in age ;^ 

 but of late years it has been referred to the Permian formation, as shown by the Fal. 

 catopterus being termed " Permian " by Sir P. Egerton in the ' Quart. Jour. Geol. Soc./ 

 voL vi, p. 9j and by Mr. Morris in his ' Catalogue of British Eossils,' 2nd edit., 1854, 

 p. 336. Its geological place has not yet been determined by the geological surveyors, 

 and for the present I prefer to regard it as of Permian age. 



The stratigraphical position of the red marl and sandstone of Rhone Hill (Tyrone) is 

 noticed at p. 481 of Portlock's ' Report Geol. Londonderry,' &c. The red marl is re- 

 garded as the same as that underlying the Chalk and Greensand at Benbradagh (London- 

 derry), and having a thickness there of between 600 and 700 feet, and overlying marls 

 and sandstones, not less than 1000 feet thick, to which succeed the Carboniferous and 

 Devonian strata. 



6. EsTHERiA MiNUTA, Alberti,^^. PL I, figs. 28—30 ; PI. II, figs. 1—7 ; PL V, figs. 8, 9. 



PosiDONiA MINUTA, Albevti. Von Decheris De la Beche's Handbuch der Geologie, 1832, 

 p. 453. 



— GoLDFUSsii, Alberti (?). Ibid. 



— Keupertana [vel Keuperina], Voltz. Ibid. 



— MINUTA (Goldfuss), Alberti. Jabrbuch f. Min., 1832, p. 227. 



— — (^Alberti), Zieten. Die Versteinerungeu Wurttembergs, 1833, p. 72, 



pi. 54, fig. 5. 

 . — — {Goldfuss), Alberti. Monograpbie, &c., 1834, pp. 114, 120, 121, 202. 



— — Goldfuss. Petrefact. Germanise, parsii, 1834-40, p. 118, pi. 113, fig. 5. 



— — Voltz. Mem. Mus. Nat. Hist. Strasbourg, 1837, vol. ii, p. 7. 



— Albertii, Volts. Ibid. 



PosiDONOMYA MINUTA, Bronn. Leth. Geogn. (1835-38), vol. i, p. 164, pi. 11, fig. 22. 



— — Strickland and Murchison. Transact. Geol. See, 1840, 2d ser,, 



vol. V, p. 337, pi. 28, fig 4. 



— — Bronn. Letb. Geogn., 3rd edit. (1851), vol. ii, part 3, p. 60, pi. 



11, fig. 22. 

 EsTHEKiA MINUTA, Rupert Jones. Quart. Journ. Geol. Soc., vol. xii, p. 376. 



■o c- 1 • (Heigbt of valve... -^incb) ^a.. ^,^ i i 



From Sinsbeim \^ ° , ^i ^Proportion 16 to 21, or 1 : 1 



(Lengtb ^| „ ) 



1^^'^^* 1^2 » "^Proportion 18 to 27, or 1 : H. 



(.Length 4 » 3 



THeight, more ttan ^ 



. , f- Proportion 1 to 1|. 



(.Length -i- „ 



From Sulzbad, var. fHeight, less than t-V „ , 



.„ .- \ f Proportion 7 to 12, or 1 : If— 



Albertn (Length i. ' ^ * 



1 We must remember, however, that each of the terms "New Red Sandstone" and "Poikolitic" 

 comprised, until about 1841, both the "Upper Red Sandstone" and the "Lower Red Sandstone," the 

 latter of which was then divided oiF, with the magnesian limestone, under Murchison's term " Permian." 



