WOODWARD : FOSSIL FISHES OF THE UPPER LIAS OF WHITBY. 35 
characteristic median vertical ridge. Each scale of the series of the 
" lateral line " is pierced by a foramen with partially raised rim. 
Specifically Indeterminable Remains of Eugnathus or 
Heterolepidotus. 
1844. Lejjidotus riigosiis, L. Agassiz, Poiss. Foss., vol. ii., pt. i., p. 
246 (in part), pi. xxxiii a., fig. 4 (non 
figs. 1, 3, 5, 8). 
1844. Aspidorhynchus anglicus, L. Agassiz, p. 139 (name only). 
1843-52. Lepidotus pectinatus, P. M. G. Egerton, Proc. Geol. Soc, 
vol. iv., p. 183, and Figs, and Descript. 
Brit. Organic Remains, dec. vi. (Mem. 
Geol. Siirv., 1852), no. 3, pi. iii. 
The name of Lepidotus rugosus is given by Agassiz to mis- 
cellaneous fragmentary remains which will be discussed later, but 
which comprise one portion of squamation from the Upper Lias of 
Whitby almost certainly referable either to Eugnathus or to the 
nearly identical genus Heterolepidotus. This specimen is now in the 
British Museum, and on comparison the scales are observed to be 
much more closely similar to those of the typical Heterolepidotus 
from Lyme Regis than to those of Lepidotus. They are more delicate 
than the scales usually are in the latter genus ; but it is unfortunate 
that the overlapped margin cannot be distinctly seen, to determine 
whether or not the anterior angles are produced forwards. 
Careful examination and comparison of the imperfect jaw from 
the Upper Lias of Whitby, named Aspidorhynchus anglicus by 
Agassiz (Brit. Mus., No. P.450), indicates that this fossil must 
also be referred either to Eugnathus or Heterolepidotus. It is a 
much-abraded ramus of the mandible, with remains of the conical 
teeth, and a figure of the specimen is given in the Catal. Foss. Fishes, 
Brit. Mus., part iii. (1895), pi. viii., fig. 2. 
The imperfect fish described by Egerton under the name of 
Lepidotus pectinatus, is too unsatisfactory both for generic and 
specific determination ; but this also very probably represents an 
unknown large species of Eugnathus or Heterolepidotus. The pec- 
tination of the scales is confined to the abdominal region, where 
