32 WOODWARD : FOSSIL FISHES OF THE UPPER LIAS OF WHITBY. 
The arrangement of the fins is shown in the imperfect specimen 
represented in pi. iv., fig. 5. A fragment of the dorsal fin {d.) is 
opposed to remains of the pelvic pair {ph.) ; and the anal fin (a.) 
seems to have arisen midway between the latter and the caudal (c). 
The last-mentioned specimen also affords the best view of the 
squamation. Some of the scales of the flank are deeper than broad, 
even in the hinder half of the caudal region ; and when their pos- 
terior border is preserved, it seems to be gently convex without any 
trace of serrations. The feeble rugose ornament, characteristic of the 
species, is scarcely perceptible except on the hinder two-thirds of the 
caudal region ; and even here the direction of the light must be care- 
fully adjusted before it can be distinctly observed. The rugae are 
most conspicuous on the anterior half of the scale ; they are rounded, 
sometimes more or less blended or branching, and there is often a 
distinct tendency to their passing into fimbriations at the superior 
and anterior borders. A few of the scales of the ''lateral line" 
exhibit a deeply-oval foramen for the passage of the sensory canal. 
In addition to the Whitby fossils thus described, the collection 
of the British Museum comprises numerous typical examples of 
PhoUdophorus germanicus from the Upper Lias of Wiirtemberg. 
As already mentioned, it is thus possible to determine the species 
from the Whitby Lias by the direct comparison of specimens ; and 
some of the features, not very clearly shown in the fossils now under 
consideration, can be well observed in examples from the typical 
locality. Summarizing all these essential characters, the following 
diagnosis of the species may be appended : — 
A large species, attaining a length of about 0*3m. Length of 
head with opercular apparatus somewhat exceeding the maximum 
depth of the trunk, which equals about one-fifth of the total length 
of the fish. The rugose ornament of the head and opercular bones 
very fine, but conspicuous ; maxilla and dentary longitudinally 
striated. Pelvic fins arising slightly in advance of the middle point 
of the trunk, with the dorsal fin directly opposed. Scales large and 
nearly smooth, but with a faint, coarse rugosity, most conspicuous in 
the caudal region ; their hinder margin very slightly convex and not 
serrated ; at least six longitudinal flank-series much deeper than broad. 
