476 "J- '^- '^- Ravn. 



In the neighbourhood of the cardinal margin and in front of the 

 umbo a somewhat excavated region; between this and the cardinal 

 margin an oblong, small but strong prominence, and in front of this 

 a larger projection (imprint of the anterior adductor), which is lost 

 below. Behind the umbo a depression which runs in an oblique 

 direction towards the posterior part of the ventral margin, though 

 not reaching quite to the latter; it is bounded posteriorly by a 

 projecting part (imprint of the posterior adductor). Along the posterior 

 part of the cardinal margin a broad furrow, which vanishes after 

 passing a small, marked depression lying above the impression of 

 the posterior adductor. The impressions of the adductors not distinctly 

 marked off; the palliai line without sinus. Of teeth only 1 cardinal 

 tooth apparent in each valve, that of the left valve lying in front of 

 that of the right. 



As mentioned, the form varies considerably, as is shown by the 

 following measurements of two casts : 



Height Length Thickness 



32 mm 68 mm '20 mm 



37 — 54 — 17 — 



All transitions seem to occur between the extreme forms, so that 

 all the available specimens probably belong to one and the same 

 species. — A few fragments preserved of the shell itself show, that 

 the surface of the shell has been covered with the usual, concentric 

 lines of growth. 



During the Danish Expedition to the east coast of Greenland in 

 1891 — 92 a single cast of a left valve of the same or a very nearly 

 related s])ecies was found at Cape Stewart. The incomj)leteness of 

 the material does not permit of a certain determination. Lundgren, 

 who worked up the Jurassic fossils brought by the Expedition from 

 Cape Stewart, does not mention this specimen. 



Distribution. North -East Greenland: "Kløft II" on Store 

 Koldewey Island (22 casts). In a loose-lying stone at "4. Sænkning" on 

 the same island (cast of a left valve). — In loose-lying stones from 

 the river-bed through Muschelberg on Hochstetter's Foreland (3 casts). 

 Top of Muschelberg (cast of two connected valves). 



East Greenland: ? (^ape Stewart (cast of a left vahe). 



46. Lucina substriata Roemeu? 

 1835. Lucina substriata Roemeu, Verst. des norddeutsch. OoHthen-Geb. p. 118; PI. 7, 



fig. 18. 

 1874. - — — ; Brauns, Der obere Jura. p. 285. 



I have not been able to refer some rather badh' preserAed 

 specimens of a Lucina with full certainty to any earlier described 

 species. They seem to come nearest to L. substriata, to which they 



