108 MESSRS. HANCOCK AND ATTHEY ON 



are very similar to, but they seem to be smaller than, those of 

 the other species, as pointed out by Sir P. Egerton ; they also 

 appear to have the surface more elevated and rounded. 



From the character of the scales and great size of the pectoral 

 spines, but more particularly from the difference observed in the 

 teeth, we consider ourselves justified in dividing this from the 

 A. Wardi, and beg to dedicate it to Sir P. Egerton, who was 

 the first to point out the probability of its specific distinctness. 

 We therefore propose for it the name of Acanthodopsis Egertoni. 



Gyracanthus tuberculatus, Agassiz. 



The gigantic spines of this little-understood fish occur pretty 

 frequently at Newsham and Cramlington, in a fine state of pre- 

 servation. In conjunction with Mr. J. W. Kirkby, one of the 

 authors of this paper pointed out in 1863 that these spines were 

 not, as usually thought, dorsal, but were paired spines, most pro- 

 bably pectoral.* We have now before us seventy-one of these 

 formidable weapons ; and the first thing that strikes the observer 

 is, that by far the greater number have lost the apical extremity, 

 and that they are not merely bent from front to back, but are 

 also laterally curved. On closer examination it is found that 

 there are as many bent to the right as to the left side, and that 

 of such bent spines there are just twenty-four pairs. Thus 

 twenty-three spines are left unaccounted for ; these may be con- 

 sidered straight, being bent only from front to back, and their 

 points are entire. But first respecting the paired spines : we 

 have said that they have all lost their points ; they are not frac- 

 tured, however, but are all worn smoothly down diagonally at a 

 very acute angle ; and, what is still more interesting, this wear- 

 ing always takes place at the side opposite to that of attachment. 

 Assuming, therefore, that these spines are pectoral, and that 

 they were inclined backwards and downwards, as assuredly they 

 would be, then the wearing of the points is exactly such as 



* See paper entitled "Fish Remains in the Coal Measures of Durham and Northimiber- 

 land," by Messrs. T. Atthey and J. W. Kirkby, read in the Geological Section at the New- 

 castle Meeting of the British Association. 



