10 UPPER CRETACEOUS TELEOSTS 
attached to the internal face of the operculum. A small interoperculum appears 
to be present, below the suboperculum and near to the ventral preopercular region. 
The opercular bones are smooth, as are the other dermal skull bones. 
sca.cor 
Fic. 2. Ichthyotrvinga furcata (Agassiz). Pectoral girdle of the right side in lateral view. 
Paired fins and girdles. The pectoral girdle is shown in lateral view in Text- 
figure 2. The post-temporal bears a flattened narrow dorsal limb in association with 
the occipital region of the skull. The supracleithrum articulates with the postero- 
medial region of the post-temporal, and is a short but expanded bone inclined slightly 
backwards ventrally. The cleithrum is a large curved bone, whose anterior edge is 
turned medially to form the posterior border to the branchial opening. Two post- 
cleithra are present, attached to the posterior region of the supracleithrum and 
cleithrum. The dorsal postcleithrum is oval in shape, but the ventral postcleithrum 
is thinner and more elongated. The endoskeletal girdle is indistinct. The coracoid, 
however, is expanded where it curves forwards to connect with the tip of the cleithrum. 
The pectoral fin articulates with the posterior edge of the endoskeletal girdle through 
the intermediary of four hour-glass shaped radials. The pectoral fins are large and 
appear to have a variable number of fin rays, between 16 and 20. The rays are seg- 
mented and bifurcated distally. 
The pelvic girdle consists of a pair of elongated triangular bones lying in the mid- 
ventral region of the body wall. The bones contact each other at their extreme 
anterior ends and posteriorly by medial bony processes behind the fin insertion, this 
being in advance of the origin of the dorsal fin. Each fin consists of approximately 
II rays, similar in form to those of the pectoral. 
