CERASPIDJE. 
233 
Family CERASPID^E. 
An imperfectly definable family, of uncertain position, known 
only by the detached dermal plates ; these plates consisting of a 
very thick middle layer of cancellous tissue, an inner squamous 
fever, and a thin outer layer with a fine superficial ribbed ornament. , 
Qft&SS P\S PlS tv.rM.T. tqua a-m.tf-H- O 0 v * 
—" Genus GERASPfS, Schliiter. 
’ Uli, Utu IratiU. 
[Sitzungsb. niederrhein. Ges. Bonn, 1887, p. 120.] 
The type and only known genus. Body deep, with a sharp 
longitudinal dorsal ridge. 
The structure of the shield suggested to Schluter the associa¬ 
tion of this genus with the Pteraspidae ; but the examination of a 
large series of specimens in the Museum of Comparative Zoology, 
Cambridge, Mass., has led the present writer to refer the proble¬ 
matical fish to the Antiarcha. One specimen shows two much 
elevated azygous plates in direct apposition one behind the other, 
very similar in form and proportions to the median dorsal plates of 
Pterichthys rhenanus ; the posterior plate, however, is relatively 
larger, has an especially deep keel, and seems to have been pro¬ 
duced into a posterior horn. Another plate is very similar in form 
to a ventro-lateral of Pterichthys ; and it may be added that, where 
thickened, the plates of the Asterolepidae fiave an inner cancel¬ 
lated structure precisely similar to that observed in the fossils now 
under discussion. 
Ceraspis carinata, Schluter. 
1887. Ceraspis carinatus , C. Schliiter, Sitzungsb. niederrhein. Ges. 
Bonn, p. 120. 
1887. Ceraspis hayenensis, C. Schliiter, ibid. p. 122. 
Type. Imperfect dermal plates ; University Museum, Bonn. 
The type species, of moderate size. The horn-like process of the 
hinder dorsal plate ( carinatus) much laterally compressed, with 
smooth, flattened, longitudinal ribs, very closely arranged, some¬ 
times intercalated and bifurcating. Anterior median dorsal plate 
(hayenensis) much longer than broad, with a sharp longitudinal 
median keel rising to an obtuse apex behind its middle point: the 
sides of the plate facetted and marked with fine ridges parallel to 
the outer border. 
Form. Sf Loc. Middle Devonian : Eifel. 
36160. Imperfect large horn-like plate, showing the superficial 
ribbed ornament above, and the inner cancellated tissue 
towards its base ; Gerolstein. Purchased , 1861. 
