LETTER FROM SIR RODERICK MURCHISON. 149 



much pressed against each other, and imbricated like 

 the scales alongside of the great anterior ' rayons ' of 

 these fins, replace in this case the spinose rays which 

 support the fins of the two genera, Acanthodus and 

 Cheir acanthus" We believe that your specimens belong 

 to the C. Traillii Agass., found in Pomona, Orkney, by 

 Dr Traill. There may be two species in those you have 

 sent, but it seems doubtful. 



' As to the fossils 1, 2, 3, we know nothing of them 

 except that they remind me of the occipital fragments of 

 some of the Caithness fishes. I do not conceive they 

 can be referable to any reptile, for if not fishes, they more 

 clearly approach to crustaceans than to any other class. 

 I conceive, however, that Agassiz will pronounce them 

 to be fishes, which, together with the curious genus 

 Cephalaspis of the Old Red Sandstone (described at 

 length from the Scotch and English specimens), form 

 the connecting links between crustaceans and fishes. 

 Your specimens remind me in several respects of the 

 Cephalaspis. 



1 Although my work was intended to be exclusively 

 devoted to Silurian (or transition) rocks of England and 

 Wales, I have made a few allusions to other tracts, and 

 among these to the Old Red Sandstone of Scotland, in 

 doing which I have, in the descriptions of the organic 

 remains, briefly alluded to your labours. Now that I 

 know the fidelity and closeness of your research, I shall 

 endeavour to introduce another allusion in the Appen- 

 dix, which is all that remains unprinted. 



' I am delighted with your clear and terse style of 

 description, and beg to assure you that if you could 

 send us in the course of the summer any general and de- 

 tailed account of both the Sutors and all their contents, 

 I shall have the utmost pleasure in communicating it to 



