186 
ACTIN0PTEBYG1I. 
impression of the external aspect of the roof on the 0 ^ 
side of the fossil, this bone is not exposed above. 
I)arietals (pa.') are an unsymmetrieal pair P 9 
broader than long, meeting throughout their len^t ^ 
a slightly sigmoidal suture, and marked by about _ 
ridges which extend from border to border, while 0 ^ 
short ridges and tubercles are observed behind. ^ 
squamosals (sq.) seem to have been very narrow 
insignificant plates at the postero-lateral angles ° 
skull, not extending further forwards than the P arl ® ^ 
The frontals (fr.) extend and expand backwards to 
anial rooi , 
more than half the postorbital region of the crania t® ^ 
and these are not a symmetrical pair, that o i the r^^ 
side being wider and extending further backwar s . g0 
that of tbo left side. The few ornamental ridges on ^ 
bones do not quite reach the hinder margin and are .| ta j g 
way connected or correlated with thoso on the P arl . ^ 
The very narrow interorbital region is compara 
stout, and impressions suggest that a delicate cre £ 0 
shaped wing extended upwards and outwards ^ rom ^ c _ 
frontal on each side to protect the relatively la ’.- 1 
ball. The anterior end of the frontals seems 
expanded a little again on the rostral region, two 
of membrane-bone being crushed in the fossil on ^ qoh- 
of the ethmoid and those are apparently direct y ^ ^ 
tinuous with the frontals. The orbit (orb.) OOCU Pj^ er ior 
quarter of the length of the skull, and at its aU . tCf 
border on each side there is a thin, ovoid, con' e. 
which seems to be a dermal or membrane-bom 
well-ossified mesethmoid (elh.) is marked by n u ^ 
fine longitudinal ridges terminating a little e *V QUg jj. 
anterior end, which is scarcely expanded but is c 11 ^ 
truncated and hollowed in front in such a way as ^ 
it the appearance of being a tube. The cius j extend 
bones lie on either side of the rostral region, an acutc 
for a short distance in advance of it, tapering to 9 . D 0 te 
point. The bases of a single regular close series o^ jjj,, 
teeth in the dentary are observable on the bit s: L^edia® 
mediately behind the occiput, and pointing t° 1 (p.t.) 
re-entering angle, the pair of post-temporal p a ^ ^an 
is preserved ; each being triangular in shape, ^g^ind 
broad, and unornamented on its outer face. gcU tes, 
these again is one of the narrow heart- shape 
