460 DR. W. G. BIDEWOOD ON THE CRANIAL [DeC. 13, 



which in the circumstances was not permissible. The pro-otic 

 bulla is elongated in a direction transverse to the axis of the 

 skull, and in a posterior view of the cranium a portion of the 

 squamosal bulla is visible on the mesial side of the descending- 

 ridge of the epiotic bone. An auditory fenestra is present. 



The opisthotic bone is small and flat ; the orbitosphenoid does 

 not extend to the prefrontals ; and there is no distinct fenestra 

 between the mesethmoid and the frontal bones, although the 

 anterior ends of the right and left frontal bones are separated 

 by a narrow space. The parasphenoid has the same relations 

 as in Clupea\ there are no teeth on the parasphenoid and 

 vomerine bones. 



The post-temporal and supratemporal bones resem.ble those 

 of Cliqjea, except that both are relatively shorter. There is a 

 small nasal on each side of the head, and seven bones around 

 the eye. 



Vestigial teeth occur on the edges of the premaxilla and 

 maxilla. The maxilla and two surmaxill?e are of greater vertical 

 extent and less horizontal extent than in Clupea. The mandible 

 is rather short and high, and the highest point is over the middle 

 of the length of the ramus. The angular bone is small and 

 distinct. There are six or eight minute teeth at the front of 

 each dentary bone. 



The hyomandibidar articulates with the cranium by a single 

 broad head. The ectopterygoid is sharply bent, even more so than 

 in Clupea harengus.- The buccal surfaces of the entopterygoid, 

 ectopterygoid, and palatine are covered with a kind of shagreen 

 of closely-set, minute denticles. 



The bones of the opercular series are much the same as in 

 Clupea harengus, but they are relatively smaller. The interhyal 

 is ossified. The urohyal has the form of a thin, triangular plate 

 of considerable vertical extent. 



The fourth epibranchial is relatively less expanded than in 

 Clup)ea. The three basibranchial bones, the glossohyal, and the 

 first and second hypobranchials are covered with a shagreen of 

 denticles similar to that found on the entopterygoid. 



Pellonula vorax. 



Pellonula vorax (Brit. Mus. 89.11.20.11, Stanley Falls) has a 

 skull which bears a fairly close resemblance to that of the 

 Herring. The upper surface of the cranium is smoother, and 

 the part of the ci-anivim behind the orbit relatively shorter. 

 The bony bullae resemble those of Pellona rather than those of 

 Clupea, and a portion of the squamosal bulla is visible in a 

 posterior view of the cranium on the mesial side of the descending 

 ridge of the epiotic bone. The exoccipitals and basioccipital were 

 not present in the specimen examined, so that the presence of an 

 * auditory fenestra could not be determined. 



The orbitosphenoid does not extend to the prefrontals. A 



