100 Proceedings of the Royal Physical Society. 



I am therefore of opinion, that the bodies in question have 

 nothing to do with " carpal bones;'' or with the endoskeleton 

 of a shark at' all, but that they were, on the other hand, 

 dermal appendages, which may probably enough have been 

 situated in the neighbourhood of the pectoral fin, the thin or 

 open side being proximal and the apex distal. The want of 

 enamel, or of sculpture on any part of the surface, shows 

 that they must have been covered with a thin layer of skin. 

 Their frequent occurrence in close relation to the spines of 

 Gyracanthus renders it, indeed, highly probable that they 

 belong to the same fish. 



I hope, on a future occasion, to enter more minutely into 

 the microscopic structure, both of these bodies, and of the 

 Gyracanthics-si^inQS, themselves. 



3. On two new Species of Gyracanthus. 



In the Geological Magazine for last month (N"ov. 1883) 

 I have given brief diagnoses of two new species of this genus 

 from the Carboniferous Limestone series of Scotland, concern- 

 ing which I propose, in the present communication, to enter 

 a little more into detail. 



Gyracanthus nohilis — Traquair. 



Gyracanthus tuber culatus (Trsiq.), Geol. Mag., dec. ii., vol. viii,, 1881, p. 34. 

 Gyracanthus nobilis (Traq.), Ibid., dec. ii., vol. x., 1883, p. 542. 



The spines which I have named Gyracanthus nohilis are of 

 common occurrence in the ironstone worked at Borough Lee, 

 near Edinburgh, belonging to the Middle Carboniferous Lime- 

 stone series of Central Scotland ; and I have also seen a frag- 

 ment from a similar horizon at Cowdenbeath, in Fifeshire. 

 At first I confounded them with G. ttcherculatiis (Ag.), but the 

 accession of more extensive material, along with a closer in- 

 vestigation of the subject, soon convinced me of their specific 

 distinctness. 



Gyracanthus nohilis attains a large size. One spine in my 

 own collection, wanting a small portion of the base, but having 

 its extreme point preserved, measures 21 inches ; had it been 



