E. Bullen Newton — On Archanodon Jukesi. 249 



an interesting paper on Anodonta Jukesi, in which he compared the 

 Irish and Northumberland habitats of this mollusc with the sand- 

 stone deposits of the Catskill Series of New York State, regarded 

 variously as Upper Devonian or Lower Carboniferous, containing 

 a large bivalve known as Cypricardites Gatskillensis, and which he 

 considered as a form closely analogous to A. Jukesi. 



Professor Amalitsky ' during 1895 established the new genus of 

 Palceanodonta, selecting for his type Unio casto7' of Eichwald 

 (Lethaea Eossica, 1861, p. 1,003, pi. xxxix, fig. 20), including in it, 

 among other forms, Anodonta Jukesi. 



Finally, it may be stated that the Monmouthshire specimen, now 

 about to be described, was exhibited during the early part of 1895 

 at one of the meetings of the Geological Society of London,'* and is 

 referred to in the printed " Pi'oceedings " as follows : " A specimen 

 with Anodonta from the Lower Old Eed Sandstone of Talgarth 

 (Llanvaches), by Caerleon (Mon.), exhibited by Professor H. G. 

 Seeley, F.E.S., on behalf of Percy Hawkins, Esq." 



Description of the Specimen. 

 Genus AECHANODON, Howse, 1878. 

 Nat. Hist. Trans. Northumberland, vol. vii (1878), p. 173, pi. xiv. 

 Type. — Anodonta Jukesi, W. H. Baily. 



Synonyms.— ^nodcn, E. Forbes MS., 1853 ; Anodonta, W. H, Baily, 

 1861 ; Amnigenia, Hall, 1883 ; Palceanodonta, Amalitsky [pars), 1895. 



Archanodon Jukesi, W. H. Baily. 

 Anodon Jukesi, E. Forbes : 22nd Eep. British Assoc, 1853, p. 43. 

 Anodonta Jukesi, W. H. Baily : 28th Eep. British Assoc, 1859, p. 75 ; 

 •' Explanations to Sheets 147 and 157 of the Maps of the 

 Geol. Survey of L-eland," 1861, p. 16, fig. 3. 

 Archanodon Jukesi, Eichard Howse : Nat. Hist. Trans. Northumber- 

 land, vol vii (1878), p. 173, pi. xiv. 

 Palceanodonta Jukesi, W. Amalitsky : Quart. Journ. Geol. Soc, vol. li 

 (1895), p. 346. 

 The remains of this shell as represented on the sandstone slab 

 from Monmouthshire consist of two casts or moulds of the interiors 

 of left valves and a fragmentary right one. They have apparently 

 escaped compression during fossilization, the original convexity of 

 the specimens being well preserved. The valves are elongate, sub- 

 cylindrical, convex, and sloping from the lateral summit to the 

 ventral margin at an angle of about 20 degrees ; anterior area 

 rounded and short, posterior produced and obtusely angulated from 

 the beaks to the margin ; the urabones are depressed, not prominent, 

 and very anterior ; the cardinal line is edentulous, straight, and 

 elongate, extending to within about 40 mm. of the posterior margin ; 

 the pallial and adductor scar impressions are only very feebly seen 



1 "W. Amalitsky, " A Comparison of the Permian Fresh-water Lamellibranchiata 

 from Russia with those from the Karoo System of South Africa" : Quart. Journ. 

 Geol. Soc, vol. li (1895), p. 346. 



' Quart. Journ. Geol. Soc, vol. li (1895) : Proceedings, p. vii. 



