100 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 5, 



they are closely allied to Cephalaspis Lloydii and C. Lewisii. This 

 fact will probably be sufficient to remove all doubt that the beds in 

 which they occur form part of the Old Red Sandstone. 



Traces of these remains have been recently found in the tilestone 

 beds at Northfield, Shobdon, by the Rev. J. F. Crouch, President 

 of the Woolhope Field Club. 



Appendix. 



Prof. Huxley and Mr. Salter have carefully examined the cephalic 

 bucklers referred to above, and have compared them with the remains 

 of previously described species ; and Prof. Huxley is now minutely 

 examining their structure in order to determine their true relationship, 

 either to Crustaceans or to Fishes. In the meantime, and until we 

 may hope for a complete account of these fossils, I have been favoured 

 by the above gentlemen with short descriptions of the two figured 

 species, which are easily distinguishable from those found in the 

 Cornstones of the Old Red Sandstone. 



*«Pteraspis, Kher*, 1847. 



As it is evident, — whether these shields be eventually referred to 

 Fish, as suggested by Agassiz, or to Crustaceans, to which opinion 

 some naturalists incline, — that they must be separated generically 

 from the broad cornuted heads of Cephalaspis Lyellii, we cannot do 

 better than adopt the name suggested by Dr. R. Kner. 



The characters of the two new species may stand as follows : — 



Pteraspis truncatuSy Huxley and Salter. 



P. capite elongato, ovato, regulariter convexo, antice truncato vel 

 emarginato, postice contracto, gibbo, carinato, brevispinoso : 

 superficie lineis undosis longitudinalibus distinctis tenuissime 

 interstriatis. 



Pteraspis Banksii, Huxley and Salter. 



P. capite late elliptico subdepresso, postice truncato carinato bre- 

 vispinoso, antice contracto, et utroque tuberculo marginali ; 

 lateribus planis et quasi alatis : superficie striis tenuissimis cos- 

 tulisque ornata, et ante medium capitis tuberculis 9-11 clavatis 

 e linea mediana radiantibus. 



There is another species, very like the P. truncatus, in the Upper 

 Ludlow Rock, lately discovered by the geologists at Ludlow. It will 

 be described hereafter." 



* Ueber die beiden Arten Cephalaspis Lloydii und Lewisii, Agassiz, und einige 

 diesen zunachst stehenden Schalenreste : Haidinger's Naturw. Abhandl. vol. 1. 

 p. 159, pi. 5. 



