1862.] JONES FOSSIL ESTHERS. 143 



Russia. Lingulce occur also with Estherice in the Triassic beds of 

 Germany, and certainly must be accepted as evidence of marine 

 conditions, according to palaeontological rules; but the Triassic 

 Lingula tenuissima, in successive beds, appears smaller and smaller 

 in size, until it is dwarfed and disappearing, when Estheria minuta 

 comes in ; as if more and more fresh water invaded the area, un- 

 favourably to the Lingulce, and ultimately bringing in the Estherice. 

 The Lingula bicarinata has been referred to as presenting " traces " 

 only, in some instances, in the Estherian marl of Kokenhusen ; hence 

 these Lingulce may have been " derived " fossils ; or more probably 

 they may have been truly of marine and local origin, but destroyed 

 by the invasion of the fresh water which favoured the Estherice. The 

 fossil Fishes of Scotland and Russia, associated with the Estheria, 

 do not bear any exact testimony of marine conditions (although 

 occurring in some places with truly marine fossils) ; their recent 

 allies are the Polyptericlce and Siluridce, inhabitants of rivers and 

 lakes ; and they may have been at home in both fresh and salt water. 

 2. Estheria striata, Miinster, sp., does not bear the true Estherian 

 characteristics so clearly as E. membranacea. The brown, horny, wide- 

 ridged, neatly sculptured valves of the latter are here replaced by 

 black, filmy, closely striated valves, which, however, by their tenuity, 

 their ovato-oblong shape (similar to that usual among Estherice), and 

 even by their close striation, different from that of Aviculidce and 

 Anihracomyce, and not unlike what occurs in some Estherice under 

 certain conditions of growth, appear to me to belong to this genus. 

 Their gregariousness and their associating with Eishes and Plant- 

 remains are also habits common to them and Estherice. In one in- 

 stance (Lammerton) I have seen reticulate texture in the valves, and 

 that helps to place them aright. Further, they present subquadrate 

 or rather suborbicular individuals (Lammerton), a peculiarity found 

 also with two or three known species of Estherice, — the difference of 

 form being probably of sexual significance. Lastly, in the Coal- 

 measures there are smaller Estherice, with distinct ridges, interspaces, 

 and sculpturing ; and, were the large and the small found together (as 

 the large and small of E. ovata and E. elliptica are found together 

 presenting similar differences to those under notice), I should be in- 

 clined to regard them as presenting stages of growth ; for we find 

 not unfrequently that the older individuals of Estheria cease to de- 

 velope evenly separated concentric ridges and neat uniform inter- 

 spaces, and produce layer after layer at the edge of the valve so 

 rapidly that nothing but a series of close concentric striae is to be 

 seen ; and this growth seems also to occur sometimes in small speci- 

 mens that have not had favourable conditions of growth. 



E. striata has passed about from name to name* in palaeontological 

 works ; in collections too the specimens have been doubtfully placed ; 

 and such good geologists as Mr. G. Tate and Mr. E. W. Binney 

 refused to give them a place among the Mollusca ; they indepen- 

 dently suggested an Estherian relationship for specimens which they 



* Sanguinolaria striata, Miinster and Groldfuss ; Cardiomorpha striata, De 

 Koninck. 



