142 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [I)eC. 17 



Table (continued). 



Genus and Species. 



Locality. 



Geological Stage. 



Estheria minuta, Alberti, sp, 



var. Brodieana 



Mangaliensis, Jones . . . 



ovata, Lea, sp 



Kotahensis, Jones 



concentrica, Bean, sp. 



Murchisoniae, Jones . . . 



elliptica, Dunker 



, var. subquadrata 



Forbesii, Jones 



Middendorfii, Jones.. 



Leaia Leidyi *, Lea, sp. . . 



, var. Salteriana 



, var. Williamson 



iana. 



Alsace; Hanover 



Germany (Wurtemberg, 

 &c). 



Hanover ; Worcestershire ; 

 Warwickshire ; Somer- 

 setshire. 



Gloucestershire ; Somer- 

 setshire ; Morayshire 

 (Linksfield). 



Mangali, India 



N.America (Pa. Ya.Ca. &c.) 



Kotah, India 



Yorksliire 



Skye 



Hanover 



Hanover ; Sussex 



Cacheuta, South America 



Tourga, Siberia 



Pennsylvania 



Fifeshire 



Lancashire 



Bunter. 

 Lettenkohle. 



Keuper. 

 Rhaetic. 



Triassic or Rha?tic. 

 Triassic or Rhaetic. 

 Jurassic or Rhaetic. 

 Oolite (Lower). 

 Oolite (Oxfordian). 

 Wealden. 

 Wealden. 

 Mesozoic ? 

 Tertiary ? 



Lower Carboniferous. 

 Lower Carboniferous. 

 Upper Coal-measures. 



1. Estheria membranacea, Pacht, sp., was described by me in 1859 f 

 under the name of Estheria Murchisoniana%. It is found abundantly 

 in the fish-bearing flagstones of the Old Red Sandstone of Caithness § 

 and Orkney ; and in a marl at Kokenhusen, Livonia, which belongs 

 also to the Old Red or Devonian group. This species has more nearly 

 equilateral and orbicular valves than most of the known Estheriaz, 

 and the umbones are more nearly centrade than in any except 

 E. concentrica ; the valves resembling in outline those of a minute 

 Posidonomya or Aviculopecten\\. Owing to its suborbicular shape, 

 Dr. Pander, to whom I am indebted (through Yon Helmersen) for 

 a valuable bibliographical note on this species, retains Pacht's generic 

 term " Asmusia " for this fossil ; but I do not see any necessity for 

 it, as the difference in outline between this and other Estheriw is one 

 of degree only, and not essential. 



The only fossils that are associated with E. membranacea are Fishes 

 in Caithness and Orkney, and Fishes and Lingula bicarinata in 



* Cypricardia Leidyi, Lea. t Quart. Journ. Geol. Soc. vol. xv. p. 404. 



% I thought that the name " membranacea " was preoccupied for a fossil Estheria 

 (of the Wealden) ; but, although used in collections, it had not been applied in 

 books ; and if it had, the ground of its application, namely the supposition that 

 Cyclas membranacea, Sow., is an Estheria, is baseless. Cyclas subquadrata, Sow., 

 is a Wealden Estheria. 



§ Banniskirk, Caithness, is another locality, in addition to those mentioned in my 

 1 Monograph,' judging from a specimen that I lately saw in the Newcastle Museum. 



|| Mr. S. P. Woodward suggested its crustacean character in 1854 ; and Dr. 

 Pander also regarded it in that light not long afterwards. Sir R. Murchison, 

 Mr. C. Peach, Mr. J. Miller, and others (including Dr. Pander and M. d'Eich- 

 wald in Russia) have helped me in working out the history and nature of this 

 Estheria. 



