ABT.26 REMAINS OF FOSSIL PORPOISES — KELLOGG 7 



ing by itself, in Eurhinodelphis longirostris^ much more than half of 

 the rostrum; in Eurhinodelphis cocheteuxl it is, on the other hand, 

 shorter than the rostral portion of the maxilla. Skull resembling 

 that of the Ziphioids, either slightly convex {Eurhinodelphis coche- 

 teuxi^ E. longirostris) or with a transverse crest {Eurhinodelphis 

 cristatus) . 



Maxilla and mandible, alone, bear teeth; maxilla with 37 to 60 

 conical teeth, single rooted in each maxilla; premaxilla edentulous, 

 with a rudimentary alveolar gutter, with sharp borders, which ex- 

 tends to the anterior extremity of the rostrum. It is not certain that 

 the lower jaw extends the whole length of the rostrum; per- 

 haps it was shorter (as in Ichthyosaurus longirostris) ; in any 

 case, the symphysis of the lower jaw is very long, and the mandible 

 is furnished with conical teeth, very close together, and single rooted. 



Lachrymal free, separated from the jugal by a suture; but with 

 age sometimes ankylosed with it. Olfactory foramina are large. 

 Supraorbital arch convex. Maxillae, above the orbits, especially in 

 Eurhinodelphis cristatus^ very thick (more in the male than in the 

 female ? ) . Mesethmoid ossified for a small portion of its length, as 

 in the Delphinoids; vomerine canal broad and closed above by the 

 closely approximated premaxillae. Nasals very small, very variable 

 in form, generally oval. Frontals usually contracted at the vertex, 

 forming a narrow band, but sometimes entirely covered by the 

 supraoccipital, which projects forwards strongly, and the nasals 

 which are deeply embedded posteriorly ; parietals always covered on 

 the vertex of the skull. 



The form of the different bones of the skull, especially the squa- 

 mosal, varies greatly in different individuals. 



All the cervical vertebrae are free. The atlas with the surfaces for 

 articulation with the occipital condyles sometimes extended into 

 wings on the external borders and having two superimposed trans- 

 verse processes. Axis with a strong odontoid process and, on each 

 side, a very strong imperforate transverse process. Centra of the 

 succeeding cervical vertebrae, either thin, or very thick {Eurhino- 

 delphis longirostris^ Priscodelphinus grandaevus). 



Thoracic vertebrae 10 or 11; the 8 anterior ones bearing bicipital 

 ribs ; the last 2 or 3 bearing single-headed ribs. At the eighth dorsal 

 vertebra the rib articulates by the tuberculum to the di apophysis, 

 and by the capitulum to the parapophysis ; at the ninth dorsal ver- 

 tebra the neck of the rib is joined with the parapophysis and the 

 diapophysis becomes rudimentary, or forms, in descending toward 

 the extremity of the rib, a transverse foramen with the neck ; the rib 

 articulates with the tuberculum on the neck of the separated rib. 

 The tenth dorsal vertebra bears a very strong transverse process (the 

 neck of the tenth rib, which is joined with the vertebra), and the 



