34 UPPER CRETACEOUS TELEOSTS 
posteriorly projecting spine. The whole of this expanded ventral part is thickened 
and ornamented with longitudinal tuberculated ridges. The operculum is deeper than 
it is broad with the opercular facet contained in the upper half of the anterior edge. 
The suboperculum is overlapped dorsally by the operculum and is a large bone bear- 
ing several strengthening ridges on the lateral face of the anterior region. No trace 
of an interoperculum was found in the specimens examined. 
Pectoral girdle and fin. The pectoral girdle is shown in lateral view in Text-figure 
14. The post-temporal has a flattened, slightly arched dorsal limb which is orna- 
mented with longitudinal bony ridges. The long, narrow supracleithrum articulates 
with the postero-medial region of the post-temporal. The lateral line canal passed 
through the head of the supracleithrum into the post-temporal. Ventrally the 
supracleithrum lies against the lateral surface of the uppermost region of the clei- 
thrum. 
The cleithrum is large and curved, its anterior edge being inclined medially. The 
lateral face of the cleithrum is unexpanded and smooth, although bony ridges are 
present more dorsally. The endoskeletal girdle is attached to the internal face of the 
cleithrum approximately two-thirds of the way down the bone. The pectoral 
fin is thus low on the flank and consists of 16 rays, all of which are branched and 
segmented. 
Two postcleithra are also present, both being elongated and narrow. The dorsal 
postcleithrum arises as a continuation of the supracleithrum posterior to the clei- 
thrum, and the ventral postcleithrum forms a direct continuation of the dorsal one. 
Both are curved and lie internal to the fin rays. 
Median fins and tail, The median fins are shown in the restoration of the complete 
skeleton in Text-figure 15. The dorsal fin consists of approximately 14 rays and is 
situated mid-way along the back between the occiput and the base of the caudal fin. 
The first ray is unbranched, unlike the remainder which are all branched. The 
proximal radials are elongated and the first few are expanded, particularly the 
anteriormost which bears an enlarged median keel. 
The anal fin is composed of 11 rays and situated behind the level of the rear end of 
the dorsal fin. The first ray is unbranched as in the dorsal fin, but unlike the dorsal 
fin none of the proximal radials is expanded. 
The skeleton of the caudal fin is impossible to describe with any accuracy. There 
appear to be either three or four preural vertebrae and two ural vertebrae incorpor- 
ated into the fin skeleton. The number of principal caudal fin rays is 19 of which 17 
are branched. Shorter and unbranched accessory fin rays are present both above 
and below the caudal fin, approximately 20 in all. 
Vertebral column. The entire vertebral column is shown in the restoration of the 
skeleton in Text-figure 15. It is made up of approximately 43 vertebrae, of which 26 
are caudal. The individual centra are about as long as deep and slightly mesially 
constricted. The neural arches are separate ossifications to the centra, those of the 
anterior precaudal region being displaced from the centra. More posteriorly the 
neural arches are more intimately united to the corresponding centra. Prominent 
