106 UPPER CRETACEOUS TELEOSTS 
The supracleithrum is long and narrow, with an antero-posteriorly elongated head. 
The lateral line canal passed straight through the head of the supracleithrum within 
a tube. Ventrally the supracleithrum lies against the upper lateral face of the 
cleithrum, and here the supracleithrum bears several vertical striations on its 
lateral face. 
Fic. 46. Eurypholis boissievi Pictet. Pectoral girdle of the right side in lateral view. 
The cleithrum (post-clavicular plate of Woodward, IgoI : 208, fig. 7) is a very 
large and characteristically shaped bone. The anterior margin is inclined medially 
where it forms the posterior boundary of the branchial opening, and the lateral 
face is greatly expanded both anteriorly and posteriorly, particularly in the ventral 
region. The anterior termination of the cleithrum les medial to the extreme 
ventral end of the preoperculum, and the posterior end of the cleithrum extends for a 
considerable distance backwards below the pectoral fin. Both of these extremities 
are acutely pointed. The ventral region of the cleithrum, as well as being expanded 
anteriorly and posteriorly, is also inflected strongly towards the mid-ventral line of 
the body, approaching its partner from the opposite side. The whole external face 
of the cleithrum is ornamented with the characteristic tubercles, which are most 
prominent near the anterior and the ventral edges. Dorsally the cleithrum tapers 
and lies medial to the supracleithrum. 
The endoskeletal girdle attaches to the internal face of the cleithrum, but owing 
to the great expansion of the cleithrum its outlines are not determinable: a large 
