WOODWARD : FOSSIL FISHES OF THE UPPER LIAS OF WHITBY. 37 
at Whitby and in Wiirtemberg reveal certain errors in the original 
interpretation by Agassiz. 
The type specimen of Ptycholepis bollensis thus needs a new 
description in the light of present knowledge. It is much shattered 
and fractured, but displays the head from the ventro-lateral aspect, 
the greater portion of the trunk, the paired fins, and the base of the 
caudal fin. The remains of the cranial and facial bones are orna- 
mented with coarse but closely arranged rounded ridges, which are 
mostly directed longitudinally ; and the same ornament is continued 
over the operculum and suboperculum, so far as preserved. The jaws 
are too imperfect for description ; but between the rami of the man- 
dible there are fragments of very broad branchiostegal rays, and, 
apparently, a gular plate, all these destitute of external ornamenta- 
tion. Tliere is also a narrow smooth plate, with partly fimbriated 
hinder margin, immediately behind the opercular bones. Nothing is 
seen of the internal bones of the trunk, for the squamation is thick, 
and, although it is much disturbed, it still completely covers the 
skeleton. Tlie pectoral fins are apparently cruslied together and 
consist of stout rays, which are only articulated and divided towards 
the distal end ; the foremost ray bears traces of small fulcra. The 
right pelvic fin (described by Agassiz as " anal ") is smaller though 
similar. None of the rays exhibit any ornamentation. The median 
fins are all lost, except a small part of the base of the caudal. The 
trunk is crushed in the same direction as the head, and the very 
narrow ventral scales thus predominate. These are excessively 
narrowed and marked by two or three of the characteristic rounded 
longitudinal ridges. Even the scales, which evidently belong to the 
middle of the flank, are longer than deep, and several of these are 
displaced, exhibiting the broad and smooth overlapped area. All of 
the latter are highly ornamented with the longitudinal ridges, which 
abruptly terminate at the anterior margin, but usually become fused 
together behind, while the posterior margin of the scale is coarsely 
serrated. In fact it may, perhaps, be more correct to describe the 
scales as longitudinally furrowed, the delicate furrows extending to 
the anterior, but not to the posterior margin. The only specially 
modified scales are observed on the ventral median line, one between 
