DISCOTOKT OF A mmiL trnmimi^ CI5TACEAN, With TtlBlHCUT.ATE 
Among the fossil remains of cetaceans obtained a short time 
since "by the National Museum from the Miocene formation of Maryland, 
is a nearly complete skeleton of a porpoise, which, on examination, 
proves to be a delphinoid form, that is, a species which m&y be referr- 
ed to the family Belphinidae, but has tuber culate teeth. This impor- 
tant specimen enables us to solve, in part, the hitherto unsolved prob- 
lem of the origin of the typical porpoises of today 
It now appaiuffs 
unquestionable that they were derived from forms "having teeth with tub- 
erculate or serrate crowns, rugose enamel, and anterior and posterior 
longitudinal ridges. 
This form of teeth is indicated in the recent 
delphinoid genus Stsno , in which the crowns have rugose enamel, and, 
as I have lately discovered, traces of anterior and posterior ridges. 
The beak in the fossil species is short and broad, the sym- 
physis of the mandible moderately long, as in Sten o, the supraorbital 
plates of the frontal large, the cervical vertebrae all free, the at- 
las wuth a single transverse process, the thoracic, lumbar, and caudal 
vertebrae short, the transverse processes of the lumbar s long, narrow, 
and not expanded at the extremity. 
It is probable that the earlier ancestral forms of the Del- 
phinidae were allied to Squalodon and that the families Delphinidae 
and Squalodontidae are offshoots from a common stem. Nevertheless, 
