PHYLL0LEPID2E. 
313 
Museum of Natural History. A single species is described as follows, 
but there are no examples in the Collection:— 
Asterosteus stenocephalus , J. S. Newberry, Rep. Geol. Surv. Ohio, 
yoI. ii. pt. ii. (1875), p. 36, pi. liv. fig. 1, and Palaeoz. 
Fishes N. America (Mon. U.S. Geol. Surv. no. xvi. 1889), 
p. 45, pi. xxx. fig. l.--Corniferous Limestone (Lower 
Devonian); Sandusky and Delaware, Ohio. [Cranial 
shield ; Columbia College.] 
AT. JA. , _ - , 
44 tcto ffatf S' * 6 J 1 * p- * py 
Family PHYLLOLEPIDiE. >7 
An imperfectly definable family, of uncertain position, probably 
related to the Coccosteidae. Dermal plates very thin, and marked 
by a superficial ornament of rugae, more or less following the con¬ 
centric or radiating lines of growth. 
Synopsis of Genera. 
Superficial rugae concentric .... Phyllolepis (p. 313). 
Superficial rugae radiating. Holonema (p. 314). 
Genus PHYLLOLEPIS, Agassiz. /?■ T 
fair 
[Poiss. Foss. V. G. R. 1844, p. 67.] ft?* S~4 f. 
Dermal plates concentrically marked with more or less irregular 
and wavy rugae. 
These problematical fossils have hitherto only been found isolated, 
* and are - rarely met with unbroken. By most palaeontologists they 
are associated with the Holoptychian Crossopterygii, whileuFritsch 
has compared them with head-bones of Palaeozoic Dipnoi. We 
venture, however, to adopt the suggestion of Newberry that the 
plates are truly referable to some so-called “ Placoderm,” though 
we would compare them with Coccosteus and its allies rather than 
with Pterichthys. 
If the last-named suggestion prove correct, this genus will also 
include the small dermal plates from the Psammites of Condroz 
(Upper Devonian), Belgium, named Pentagonolepis honincki , M. 
Lohest, Ann. Soc. Geol. Belg. vol. xv. (1888), p. 161, pi. xi. 
figs. 1-8. Moreover, the form of the dermal plates cannot be cited 
in specific diagnoses until their arrangement and homologies have 
been determined. 
