526 



FOSSILS OF THE 



[Ch. XXVI. 



Grampians consists of gray paving-stone and roofing-slate, with asso- 

 ciated red and gray shales ; these strata underlie a dense mass of con- 

 glomerate. In these gray beds several remarkable fish have been 

 found of the genus named by Agassiz Cephalaspis, or " buckler- 

 headed," from the extraordinary shield which covers the head (see 

 fig. 589), and which has often been mistaken for that of a trilobite 

 such as Asaphus. 



Fig. 589. 



Cephalaspis Lyellii, Agass. Length 6| inches. 

 From a specimen in my collection found at Glammiss, in Forfarshire ; see other figures, 



Agassiz, vol. ii. tab. 1 a and 1 &. 

 a. One of the peculiar scales with which the head is covered when perfect. These scales 

 are generally removed, as in the specimen above figured. 

 5, c. Scales from different parts of the body and tail. 



A species of Pteraspis, of the same family, has also been found by 

 the Rev. Hugh Mitchell in beds of corresponding age in Perthshire, 

 and Mr. Powrie enumerates no less than five genera of the family 

 Acanthodidas, the spines, scales, and other remains of which have, 

 been detected in the gray flaggy sandstones.* 



In the same formation at Carmylie, in Forfarshire, commonly 

 known as the Arbroath paving-stone, fragments of a huge crustacean 

 have been met with from time to time. They are called by the 

 Scotch quarrymen the " Seraphim," from the wing-like form and 

 feather-like ornament of the thoracic appendage, the part most usu- 

 ally met with. Agassiz, having previously referred some of these 

 fragments to the class of fishes, was the first to recognize their crus- 

 tacean character, and, although at the time unable correctly to deter- 

 mine the true relation of the several parts, he figured the portions on 

 which he founded his opinion, in the first plate of his " Poissons 

 Fossiles du Yieux Gres Rouge." 



A restoration in correct proportion to the size of the fragments of 

 P. anglicus, from the Lower Old Red Sandstone of Perthshire and 

 Forfarshire, would give us a creature measuring from 5 to 6 feet in 

 length, and more than 1 foot across ; and Mr. Salter is of opinion 

 that P. problematicus, Ag., from the Downton Sandstone, and P. 



* Powrie, Geol. Quart. Journ., vol. xx. p. 417. 



