462 J- P- J- R AVN - 



19. Posidonomya ornati QuENSTEDT sp. 

 PI. XXXIII, figs. 2 and 3. 



1838. Posidonia ornati Quenstedt, Der Jura, p. 551; PI. 72, fig. 29. 



1883. Posidonomya ornati — ; Lahusen, Jurass. Bild. des Rjasanschen Gouv., 



p. 25; PJ. 2, fig. 8. 

 1895. — Buchi Roem.; Sthemoouchow, Posidonomya Buchi Hoem. des 



schistes de Balaclava, p. 391; PI. 1, figs. 1 — 8. 



The shell fairly small, oblique and oblong, slightly arched. The 

 cardinal margin straight, very long. The beak pointed, but little 

 projecting, curved slightly backwards. Surface covered with numerous 

 regular, dense, concentric ribs. 



None of the specimens are so complete, that measurements can 

 be given. 



Distribution. North -East Greenland: Down from "Trsekpas- 

 set" on Store Koldewey Island in a loose-lying boulder, 60 m above 

 the sea (numerous specimens). 



Russia: in deposits belonging to the Bathonian and Callovian. 



Germany: Callovian. 



20. Pinna sp. 

 Fragments of a large Pinna species were found in boulders on 

 the south side of Vesterdalen at Danmarks Havn. The available 

 material is far too insufficient to permit of even an approximate 

 determination of the species. 



21. Perna groenlandica n. sp. 

 PI. XXX1I1, figs. 4 and 5. 



The shell linguiform with pointed, but slightly curved, terminal 

 umbo. Angle between cardinal and anterior margins ca. 70°. Car- 

 dinal margin straight. Anterior margin very slightly concave, almost 

 straight, merging evenly into the ventral margin and this again into 

 the posterior margin. The surface with broad, faint, concentric folds. 

 The right valve but slightly, the left considerably arched, with the 

 highest part lying nearest the anterior margin sloping evenly down- 

 wards towards the wing. The cardinal margin with 8 — 10 broad 

 ligamentary grooves, separated by narrow interspaces. 



Right valve : height (measured from point of umbo to furthest 

 point of the ventral margin) 63 mm, greatest breadth (measured at 

 right angles to height) 35 mm and the thickness ca. 5 mm. — A cast 

 from a left valve measured: height 80 mm, breadth ca. 46 mm and 

 thickness ca. 12 mm. 



A small specimen (2(5 mm high and 16 mm broad) has most of 

 both valves preserved; otherwise there is practically nothing but casts. 



