ESTHERIA EXIGUA. 37 



7. Lastly, I have to draw attention to a very small Permian Estheria from Russia 

 (PI. I, figs. 23, 24), having some characters very similar to those above mentioned, and 

 which may possibly be ultimately fomid to be of the same species. As I do not, however, 

 feel satisfied that I have fully elucidated this Estheria {E. exigua), I prefer to keep it 

 separate (see below). Eor specimens of this Estheria, I am indebted to M. E. 

 D'Eichwald. 



Estheria tenella may thus be said to occur — 



In Russia (jF. exiyua^. Permian. 



At Oschatz, Saxony. Permian (Rothliegende). 



„ Autun, France. Permian (?) or Upper Carboniferous. 



,, Salbacli, Black Forest. Upper Carboniferous. 

 In Lancashire, England. Upper Carboniferous. 



„ Lanarkshire, Scotland. Upper Carboniferous. 



Habitat of E. tenella. — The Beyrichice at Astley (Lancashire), Anthracomym at Bradford 

 (Lancashire), and Anthracosia, Avicula, and Sjjirorbis, in Lanarkshire, seem to point to 

 at least a brackish water for E. tenella. 



4. Estheria exigua, Eichoald, sp. PI. I, figs. 22 — 24. 



PosiDONOMYA MiNUTA (Bronn.), Kuf.o7-ga. Verhand. Min. GeseU. St. Petersb., 1844, p. 63, 



&c., pi. 1, figs. 1 — 5. 

 — EXTGUA, D' Eichwald. Geogn. Russl., 1846, p. 456 ; Leth. Rossica, 1855, 



livr. iv, p. 231 ; Bullet. Soc. Imp. Nat. Mosc, 1856, xxix, 2, 



p. 559; Leth, Ross., 1859, livr. vi, p. 941, pi. 40, fig. 4. 

 Cyclas Eos, D'Eichwald. Geogn. v, Russlands, 1846, p. 466. 

 Cythbrina (Cyclas) Eos, D'Eichwald. Bullet. Soc. Imp. Nat. Moscou, xxx, part 2, 1857, 



p. 307. 

 PosiDONOMYA Eos, D'Eickwald. Lethaea Rossica, 1859, livr. vi, p. 942, pi. 37, fig. 13. 

 [? Estheria tenella, Jordan, sp. See page 31.] 



. (Height of valve, -rV inch ~) 

 The figured specimen -5 ^ ^Proportion 9 to 13, or 1 : l^ — 



(.Length, \\ „ ) 



The material at my command for the elucidation of this species is but limited. For 

 what I have, I am indebted to the kindness of M. E. D'Eichwald, of St. Petersburg, who 

 has courteously replied to my inquiries, and communicated specimens and information, 

 both in the case of this and of other species of fossil Estherice. In January, 1861, 

 M. D'Eichwald kindly favoured me with some specimens of light-grey marl, or calcareous 

 shale, bearing remains both of Estheria exigua and E. Eos. The former is represented 

 only by crumpled portions of the carapace. Of the latter, there are several minute 

 individuals. Of these, which are delicate valves, beautifully iridescent under the micro- 



