CEPHXLASPID.R. 
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. 
Hot represented in the Collection. 
A fragment apparently of the shield of Cejphalasjpis, from the 
Lower Devonian of Dickson Bay, Spitsbergen, 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.] x 
A fragment from the Devonian of Cornwall named Steganodictyum 
carteri by E. M‘Coy (Ann. Mag. Hat. Hist. [2] vol. viii. 1851, p. 48,2, ^ 
and Brit. Palaeoz. Eoss. 1855, pi. ii. a. fig. 4) is also recorded as 
Cephalaspis (?) carteri by E. R. Lankester, Eishes Old Red Sandst. 
pt. i. (Pal. Soc. 1870), p. 42. SZ-y, 
xF yoF ) r /. S£3Z/ jptp 
Genus BUICEiBASPISj Lankester. 
[Eishes 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 laminae 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 l . 
Eukeraspis pustulifera (Agassiz). 
1889. Sclerodus pustuliferus, L. Agassiz, in Murchison’s Silur. Syst. 
pp. 606, 704, pi. iv. figs. 27-32, 6 0-62 . S'- 
1889. Plectrodus mirabilis and P. pleiopristis, L. Agassiz, ibid. pp. 606, 
704, pi. iv. figs. 14-26. 
J. Harley, in Murchison’s Siluria, ed. 4 (1867), expl. to pi. xxxv. 
PART II. * n 
