10 HIU.KE. FOSSIL VERTEBHATK REMAINS IRO.M 8PJTZBEll(iEN. 



of about 5 inches. At thc smaller end its diameter is 0,3 iucli, 

 and at the larger end (represented by an impression only) it 

 is 0,7 inch. This larger end has been broken away showing 

 a liollow interiör. The lesser end has a more solid structure. 

 From one side two short conical spikes project, one to the 

 extent of 0,2 5 inch, the other is rather shorter. At their base 

 their diameter is rather more than 0,1 inch. They appear to 

 stånd in a groove traceable along 2,7 inches, one margin of 

 which^ that imbedded in the matrix, projects beyond the other. 

 At first sight the fossil might be thought a fish-spine, 

 but the conviction grows on me that it is a jaw and the la- 

 teral denticles are true teeth. This might be settled by a 

 microscopic section which without permission 1 have not liked 

 to have ma,de. 



Acrodus. 



Acrodus spitzbergensis. 



A single, but characteristic tooth 0,9 inch long and having 

 a greatest breadth of not more than 0,12 inch, imbedded in a 

 thin piece of limestone labelled (95 Is fj. 1864, Saurie Hk.) 

 plainly belonged to an Acrodus. Thc strige rather coarse, and 

 separated by proportionately wide intervals, pass off from the 

 lips of a sunken groove instead of from a raised line as in 

 all hitherto known species. I am indebted to Mr. Davies, 

 Senior, for calling my attention to this distinguishing character, 

 and a comparison, which I made of this spitzbergen fossil with 

 a large series of acrodus teeth in the British Museum, has 

 conformed its distinctiveness. 



Exoskeletal Plate. 



A remarkable triradiate bone (I am not certain whether 

 there may not have been a fourth ray) in a piece of limestone 

 labelled (19), of which another piece labelled (116) is plainly 

 the cap, both having the Swedish label: (Isfj. 1864, Saurie Hk.), 

 is probably a dermal plate. The rays rise to a central pyra- 

 midal angle. One of them is keeled, thc surface of the two 

 others is gently convex. The keeled ray is 1,5 inch long, the 

 two others were longer. The impression received from the 

 fossil on the supposition that it is a dermal plate, is that the 

 keeled ray had a median axial position and the others diverged 



