BRITISH FOSSILS. 



MONOGRAPH THE FIRST. 



PART I. On the ANATOMY and AFFINITIES of the Genus PTERY- 

 GOTUS. By THOMAS H. HUXLEY, F.R.S., Professor of Natural 

 History, Government School of Mines. 



THE genus Pterygotus was established by Professor Agassi z, in the 

 following note appended to page xix. of his well-known work, the 

 " Monographic des Poissons Fossiles du Vieux Gres Rouge" (1844) : 



" The Plate A, accompanying this monograph, represents many 

 well preserved fragments of one of those gigantic Crustacea of the 

 Old Red, collected by Mr. Webster in the neighbourhood of Bal- 

 ruddery, in Scotland. Deceived by the scaly aspect of a portion of 

 the carapace, I at first believed that this might be the type of a 

 peculiar genus of fishes, and to that class I referred Pterygotus, in 

 my enumeration of the fossil fishes of the Silurian system, published 

 in Murchison's great work. This genus, founded upon very imper- 

 fect fragments from the Ludlow rocks, is now well known, from the 

 investigations which I have been enabled to make of a new species 

 from the Old Red, discovered by Lyell, in Forfarshire, and of which 

 Mr. Webster has found more characteristic remains at Balruddery. 

 The specimens collected by Lyell are those large scutes, of which I 

 have spoken in my ' Recherches/ vol. i. p. 26, and which, in the 

 absence of the means of rigorous determination, have been seriously 

 taken for the remains of superhuman beings. 



" Dr. Buckland and I, on examining them carefully, convinced our- 

 selves that they must be the carapaces of Crustacea ; but it was only 

 in 1840 that I obtained direct proof that such was the case. In 

 fact, among the specimens collected and communicated to me at that 

 time by Mr. Webster, are fragments of carapaces, segments of the 

 tail, the natatory palettes with which the extremity of the latter 

 was provided, legs, and chelae. These remains remove all doubt as 

 to the zoological position of the fossil. It is a crustacean of colossal 

 size, having a carapace of more than a foot and a half in width, and 

 a tail about a foot wide. The dimensions of the cephalothorax, 



