1862.] JONES — FOSSIL ESTHEEIJE, 155 



in the Lower Wealden of Hanover*. E. elliptica necessarily ranks as 

 a Cretaceous fossil in geological relation to its Jurassic, Triassic, and 

 Rhastic allies j for the freshwater Wealden group merges in its typical 

 marine system of the stratigraphical series. 



13. Estheria Forbesii, Jones. — David Forbes, F.R.S., F.G.S., 

 brought many specimens of this elegant species home with him from 

 South America in 1859 or 1860. He found it in abundance with 

 plant-remains in a shale near Cacheuta, about 3500 feet above the 

 sea, on the eastern slope of the Andes, south of Mendoza ; and he 

 thinks that possibly these beds may be related to those containing 

 fossil trees that Mr. Darwin saw in the Uspallata Pass. This 

 Estheria, however, gives no clear evidence of its palaeontological age. 

 It is somewhat allied to E. ovata of North America, and still less 

 closely to E. minuta of Europe. It is probably of Mesozoic age ; but it 

 may be Tertiary. There is nothing to gainsay its freshwater origin. 



14. Estheria Middendorjii, Jones. — This is from Siberia, and 

 was recognized as Crustacean by J. Miiller f , who regarded it as a 

 Limnadia. It is one of the largest and most elegant of Estherice, 

 and is probably of Tertiary age. Mr. C. E. Austin's paper i on the 

 locality where it was found, and Yon Middendorf 's note on it in his 

 ' Sibirische Reise,' give all that is known of its geological relations. 



Remains of Plants, Insects, and Shells (Limnceus?), all obscure, 

 add little to our knowledge of its habitat ; but what they do show 

 is strengthened by the fact of the Aspius, which accompanies the 

 Estheria in great numbers, being a Cyprinoid fish, such as is found 

 in fresh water, and being also found in some of the Miocene fresh- 

 water deposits of Europe. 



Leaia. — Together with the fossil Estherice, I have described and 

 figured in my ' Monograph ' some small enigmatical fossils that occur 

 in the Carboniferous strata. Some of these were noticed twenty-six 

 years ago by Prof. W. C. Williamson and Prof. J. Phillips § ; but no 

 conclusions were arrived at as to their probable relationship. They 

 are dark- coloured, horny, thin, quadrangular valves, either lying 

 separate, or with the dorsal edges approximate, and are marked with 

 concentric furrows, running parallel with three sides of the valves, 

 and by two oblique transverse ridges crossing the valve, from the 

 umbo to the ventral angles. I know no recent Crustacean having 

 such valves ; but the horn-like appearance of the fossils, their small 

 size, and their dissimilarity to any mollusk have brought them under 

 my notice. I find that Dr. I. Lea has described and figured a cast 

 of a similar little fossil as Gypricardia Leidyi, from the red sand- 

 stone at the base of the Carboniferous series in Pennsylvania ; and 

 there are but slight differences between this form and that of the 

 specimens found by Williamson in the Upper Coal-measures at Ard- 



* Mr. Harry Seeley, F.Gr.S., assures me that he has detected the cast of an 

 Estheria, very like that found at Bulverhithe, in a specimen of Cyclas-bearing 

 marl from the Lower Purbeck beds of Durleston Bay, near Swanage. 



t A. Th. von Middendorf 's ' Sibirische Beise,' vol. i. part 1. 



\ Quart. Journ. Gool. Soc. No. 73. p. 71. 



§ Prof. Phillips suggested that they might be Trigonellites ; but this suppo- 

 sition does not appear- to me to be well founded. 



