170 
HETEROSTRACI. 
lQI) , Palaeaspis americana, Claypole. . . ^ ~ 
, * »^s)* ^ ^ JSyy'cj n£r /*/^c - Ppr^e r*. PAJj. S*x , * ^6> zT 2 6/ f> - * Ff-1. j^7 . /./. 
1884 . Taleeaspis americana (P and P. bitruncato ), E. W. Claypole, Amer. 
. pH\7( ( Naturalist, vol. xviii. p. 1224. 
' 1885. Palesaspis americana , E. W. Claypole, Quart. Journ. Geol. Soc. 
vol. xli. p. 62, woodc. fig. 7. 
(?) 1885. Poles aspis bitruncato , E. W. Claypole, ibid. p. 62, woodc. 
fi 8 ' 
^ $*«j£ /-€% f<l3** P 'S"* 
Type. Imperfect dorsal shield-; Museum of Buchtel College, Akron 
Ohio. 
A species known only from imperfect specimens, as yet incapable 
of precise definition, but apparently distinguished from P. sericea by 
the more regularly ovate form of the shield and the slightly more 
obtuse rostrum. 
The form named bitruncato, is not improbably the ventral shield 
of this species. } />, / V ,/ - 
Form. Sf Loc. Onondaga Group : Perry Co., Pennsylvania. 
P. 6132. Imperfect internal cast of shield. 
Presented by Prof. E. W. Claypole , 1890. 
P. 6133. Several fragments. 
Presented by Prof. E. W. Claypole , 1890. 
Genus C¥’A i TPSASPIS ? Lankester. 
[Pep. Brit. Assoc. 1864 (1865), Trans. Sect. p. 58.] 
Syn. Dipl aspis, G. F. Matthew, Bull. Nat. Hist. Soc. New Brunswick, 
no. vi. 1887, p. 69. 
Scaphaspis , E. R. Lankester, Rep. Brit. Assoc. 1864 (1865;, 
Trans. Sect. p. 58 (in part). 
Dorsal shield oval, consisting of four separately calcified portions 
■—a large centred disc , with a short azygous rostral plate anteriorly, 
and a pair of large cornua on the sides. Orbits not completely 
enclosed in the shield. 
In the so-called Diplcispis, and in Cyathcispis integer , the dorsal 
and ventral shields have been found in natural association ; and a 
Scaphaspis-sha.])ed shield occurs in the same beds as the type species. 
Until confirmatory evidence is obtained, we venture to regard the 
transverse division of the lateral cornua in Diplaspis as accidental. 
/ 
Cyathaspis banks! (Huxley & Salter). 
[Plate IX. fig. 3.] 
1856. Pteraspis banksii, Huxley & Salter, Quart. Journ. Geol. Soc. 
vol. xii. p. 100, pi. ii. fig. 2. 
