﻿CRPHALA8PID/E. 193 



Shield proportionately rather broad; cornua short, orbits rather 

 close together, oval, large ; tesselated divisions of middle layer very 

 small ; external surface ornamented by small, smooth, polished and 

 rounded tubercles, moderately close in position. (Traquair.) 



The shield in the type specimen measures 0*034 in length and 

 0-069 in breadth. 



Form. Sf Loc. Upper Devonian : Scaumenac Bay, P. Q., Canada. 



Not represented in the Collection. 



A fragment apparently of the shield of Cephalaspis, from the 

 Lower Devonian of Dickson Bay, Spitzbergen, is recorded by E. R. 

 Lankester, Kongl. Svenska Yetensk.- Akad. Handl. vol. xx. no. 9 

 (1884), p. 5, pi. i. figs. 4, 5. [Royal State Museum, Stockholm.] 



A fragment from the Devonian of Cornwall named Steganodictyum 

 carteri by F. M'Coy (Ann. Mag. Xat. Hist. [2] vol. viii. 1851, p. 482, 

 and Brit. Palseoz. Foss. 1855, pi. ii. a. fig. 4) is also recorded as 

 Cephalaspis (?) carteri by E. R. Lankester, Fishes Old Bed Sandst. 

 pt. i. (Pal. Soc. 1870), p. 42. 



Genus EUKERASPIS, Lankester. 



[Fishes Old Red Sandst. pt. i. (Pal. Soc. 1870), p. 56.] 



Syn. Sclerodus, L. Agassiz, in Murchison's Silur. Syst. 1839, p. 606 

 (inappropriate). 

 Plectrodus, L. Agassiz, ibid. p. 606 (inappropriate). 



Postero-lateral angles of shield produced into enormous cornua, 

 exceeding the shield in length, and provided on the outer margin 

 with a series of prominent denticulations ; a marginal row of about 

 six large quadrate cavities on each side between the two laminse of 

 the shield. 



Eukeraspis is regarded by Lankester as a subgenus of Auchenaspis, 

 on the assumption that a second dorsal shield was originally present 

 behind the one already known. The detached cornua were de- 

 scribed by Agassiz as jaws of fishes under the names of Sclerodus 

 and Plectrodus, and seem to have been first correctly interpreted by 

 Harley 1 . 



Eukeraspis pustulifera (Agassiz). 



1839. Sclerodus pustuliferus, L. Agassiz, in Murchison's Silur. Syst. 



pp. 606, 704, pi. iv. figs. 27-32, 60-62. 

 1839. Plectrodus mirabilis and P. pleiopristis, L. Agassiz, ibid. pp. 606, 



704, pi. iv. figs. 14-26. 



1 J. Harley, in Murchison's Siluria, ed. 4 (18t>7), expl. to pi. xxxv. 

 PART II. O 



