TYPE, OF THE FOSSIL CETACEAN AGOROPHIUS TYGM^^US 7 



bility of deciding whether it is composed of the frontal joined to the supraoc- 

 cipital, as in typical Squalodon, or whether it is formed chiefly by the parietals, 

 as in Agorophius. The frontal s appear to extend outward and backward over 

 the temporal fossae as in typical Squalodon and the delphinoids. In Brandt's 

 figures of S. ehrlichii the brain-case is much shorter relatively than in Agoro- 

 pMus, \)w.t this may be due to the fact that in restoring the skull not sufficient 

 space was allowed for missing parts at the middle of the skull. In its size and 

 general conformation, in the elevation of the brain-case above the rostrum, in 

 the breadth of the rostrum, and in the height of the intermaxillse, S. ehrlichii 

 strongly resembles Agorophius. On the whole, it appears to hold an interme- 

 diate position between typical Squalodon and Agorophius, and is certainly not to 

 be closely associated with the former. 



The large extension of the parietals on the superior surface of the skull in 

 Agorophius indicates that it is a primitive form and it is not unlikely that some 

 such form was the ancestor of both S. ehrlichii and typical Squalodon. That 

 Agorophius itself is in the direct line is improbable on account of the form of the 

 teeth. The single tooth which was originally found in the skull of Agorophius 

 is more specialized than those of the Squalodons. As indicated by the figures 

 in the accompanying plate, the internal and external surfaces were about equally 

 developed, as were also the anterior and posterior cusps. Only a small portior. 

 of the roots is shown in the figures, but the tooth appears to have been two- 

 rooted. There is no indication of a third root, such as is found in some speci- 

 mens of Squalodon. 



Other genera beside Squalodon which have been assigned to the family 

 Squalodontidse are Prosqualodon, Neosqualodon, Proterocetus, Phococeius, Grraphi- 

 odon and Ceterhinops. 



Of these Proterocetus is based on a portion of a mandible of extraordinary 

 minuteness, while Phococetus and Graphiodon are based on single teeth. On 

 account of the character of the material no comparisons of the importance can 

 be made with Agorophius. Prosqualodon, based on a very well-preserved skull, 

 shows a close affinity to Squalodon, especially in the backward extension of the 

 frontals and the form of the vertex, and cannot be regarded as a close ally of 

 Agorophius. Ceterhinops, based on a fragment of a skull from the region of the 

 anterior nares, resembles Squalodon so closely, especially S. servatus, that there 

 appears to be no sufficient reason for separating it from the latter genus. The 

 genus Neosqualodon. is based on the rostrum of a skull, broken off at about the 

 line of the anterior nares and the nearly complete right ramus of a mandible. 

 The skull was probably a little smaller than that of Agorophius. A number of 



