29 



CHAPTER II. 



FISH OF THE OLD EED SANDSTONE*. 



PLACODERMlf. 



Coccosteus (Ag.). 



In the C. latus (Ag.) I have observed a pair of lateral plates on 

 the anterior part of the dorsal aspect of the carapace,, which 

 seem to have escaped the notice of M. Agassiz, and are omitted 

 in his restored figures of the genus, although represented in the 

 small figure given by Mr. H. Miller in his " Old Ked Sandstone.^^ 

 Those plates are lengthened and triangular, the base in front 

 parallel with the truncated anterior margin of the great dorsal 

 plate, with which 

 one of the long 

 sides of each is arti- 

 culated ; the apex 

 reaching to about 

 half the length of 

 the dorsal plate, ter- 

 minating a little in 

 front of the lateral 

 angle on each side ; 

 the base being con- 

 nected with the 

 head and the outer 

 margin with the 

 anterior lateral ven- 

 tral plate on each 



side. Those two pe- Profile and dorsal aspect of the carapace of Coccosteus 

 Culiar plates might — ^^ shaded plates a are the dorso-lateral plates. 

 be called the " dorso-lateral plates.^' 



1 might also remark that the posterior latero- ventral plates, 

 instead of joining precisely in the middle, overlap considerably, 



* Drawings of all these species were sent to Prof. Phillips at the Meeting 

 of the British Association at Swansea for the inspection of geologists. The 

 descriptions date from the * Annals of Natural History ' for November 1848. 



t The characters of this group were noted by the author in the ' Annals of 

 Natural History ' for July 1848. 



