226 ANNALS OF SCOTTISH NATURAL HISTORY 



small patches of a superficial sculptured layer. Here the 

 ornament, as seen under a lens, consists of small closely set 

 tubercles with stellate bases, which remind us at once of 

 the sculpture of the fragmentary plates from the Devonian 

 of Russia described and figured by Agassiz as Psammosteus 

 paradoxusj- though the tubercles are rather coarser as well as 

 more irregular in shape. 



The microscopic structure of the Elginshire plates also 

 closely resembles that of the Russian Psammosteus paradoxus; 

 there being first a thin non-vascular basement layer, above 

 which the thickness is occupied by a very close network of 

 Haversian canals, while the intervening substance shows only 

 dentinal tubules without bone lacunae. 2 



Everything connected with these plates being highly 

 suggestive of Psammosteus, I decided to refer them to that 

 genus on being shown by Mr. Smith Woodward certain 

 papier-mache casts of tolerably entire plates of P. paradoxus 

 from Russia. These casts, contained in the British Museum, 

 represent concave boat-like plates much like the Elgin fossil 

 in general aspect, though smaller in size ; so that I cannot 

 doubt that the Morayshire plates now under consideration are 

 generically identical with them. As my friend Mr. Taylor of 

 Lhanbryde has rendered me great assistance in procuring 

 material for the study of these relics, I have pleasure in adopt- 

 ing for the creature the name of Psammosteus Taylori. 



The microscopic structure of the remains which have been 

 assigned to Psammosteus, suggests that they were Selachian 

 in their nature, though it is indeed difficult to imagine what the 

 appearance of such a Selachian could have been when entire. 



This is the first record of the occurrence in Scotland of 

 plates referable to Agassiz's genus Psammosteus ; for though 

 in the British Museum there are two fragments of P. arenatus, 

 Ag., said to be from the Old Red Flagstones at Wick, I 

 feel quite convinced, after carefully examining the specimens 

 in question, that there is a mistake here, and that they are 

 from a Russian locality. 3 



1 " Poiss. Foss. v. gres rouge," pi. 27, figs. 2-4. 



2 Some of the microscopic sections which I have examined were made and 

 kindly lent me by Dr. Mackie of Elgin. 



3 These specimens are in the Peach collection, and are referred to by Mr. 

 Smith Woodward in his "Cat. Foss. Fishes Brit. Mus.," part ii. p. 127. 



