432 ON THE REMAINS OF A BRITISH FOSSIL ZEUGLODON. 



ridge already described; and under the region where the ridge 

 becomes flattened, the middle of the enlarging cerebral cavity be- 

 comes flattened, though there are concave excavations on each side. 

 The suture between the parietal and frontal is deeply impressed on 

 the cerebral surface. Behind its inferior termination is, on each 

 side, another suture 1-| inch long and about -| inch above the flat 

 irregular basal surface of the specimen. The small bone thus indi- 

 cated is not quite perfect behind, where it is shown by a fracture to 

 be imbedded between the outer and inner walls of the parietal. 

 These bones have none of the usual characteristics of the alisphe- 

 noids, and are probably to be regarded as orbito-sphenoids. They 

 are about § inch wide ; and the film of parietal xternal to them is 

 about ^ inch thick. In front of these bones and internal to them 

 are concave grooves, which widen in passing forward to more than 

 & inch, which is the width of the frontal bone on each side of the 

 groove. 



Almost the whole of the skull could be reconstructed from the ma- 

 terials preserved by Dr. Wanklyn. Among other parts I noticed the 

 two egg-shaped tympanic bones, remarkable for their regular form. 



In no respect does it approach Squalodon, which not only has the 

 parietal region constructed on a different pattern, but also has the 

 teeth of different form. 



It differs from all known species of Zeuglodon in the shortness of 

 the interspaces between the teeth, and apparently in the characters 

 of the premolar teeth, as well as in the shorter form of the skull. 

 But in the absence of the specimen any detailed comparison with 

 other species must be deferred. 



The parietal and frontal fragment is about the same size as in 

 Zeuglodon brachyspondylus of Miiller, which similarly has the frontal 

 region flattened, with a sharp crest along the parietal region — which, 

 however, does not become flattened posteriorly into a narrow table 

 as in the species described ; nor has the parietal in the foreign species 

 the folded sutural junction with the frontal of our English specimen. 



I would express ray thanks to Mr. W. Davis for assistance in 

 examining the Zeuglodonts in the British Museum, and a hope that 

 Dr. Wanklyn's Zeuglodon may eventually be deposited in one of 

 our National collections. 



