464 woodward: fossil fishes of the upper lias of whitby. 
without enamel, and evidently belong to the outer covering of 
the skull. None of these can be identified; but one nearly 
quadrangular piece (.r) is larger and better preserved than the 
a. h. 
Fig. 4. — Gyrosteufi mirahilis, Ag,,MS. ; right hyomandibular, lateral aspect 
(a) and posterior aspect (6), one-third nat. size. [Brit. Mus., No. 
P. 3356a.] 
others, and shows the external tubercles disposed more or less 
along the radiating lines of growth. This bone also exhibits 
a triangular area on the right which is free from tubercles and 
