BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 25. APD. IV. NIO 5. 7 



velopment of the vertebral centra. Among the early species, 

 the form from King Charles Land is distinguished by its 

 comparatively deep and stoiit maxilla and dentary. It is 

 also soraewliat larger than iLost of the known species refer- 

 able to the same gronp. It may therefore receive the pro- 

 visional name of Le2)tolepis Nathorsti, in compliment to the 

 discoverer of the first Arctic representative of the genns. 



The same species is evidently represented by fragmentary 

 detached bones in black shale from King Charles Island. 



Explanation of Plate. 



Holoptychius nwnilifer, sp. nov. ; Upper Devonian, Bear Island. 

 Fig. 1. Impression of outer face of imperfect scale, natural size. a covered 

 portion; h exposed portion. 



Leptolepis Nathorsti, sp. nov.: Jurassic, Swedish Foreland, Kint,- Charles Land. 

 Fig. 2. Right maxilla, outer face. 



3. Left posterior supramaxilla, inner face. 



4. Anterior supramaxilla (?). 



5. 6. Eight dentary, outer face. a space for articulo-angular; J) coro- 



noid process; c symphysis. 



7. Anterior suborbital. showing sensory canal. 



8. Left operculum, outer face. a point of suspension. 



9. Eight suboperoulum, outer face (the minute antero-superior angle 



omitted in enlarged figure). 



10, Left preoperculum, outer face. 



11. (Jeratohyal. 



Figs, 2—11 represent the fossils natural size and enlarged twiee. 



