296 Bulletin American Museum of Natural History. [Vol. XXVII, 



developed especially by Cope (1S7()), Seott (1S92), Schlosser (1886), Zittel 

 (1893), Osborn (Columbia Univ. lectures), Wortman (1901-2) and Matthew 

 (1901, 1900, 1909). 



The ])rogres.s of discovery is indicated by the following brief list (com- 

 piled chiefly from Palmei''s 'Index Generum Manimalium') of the more 

 important and best known genera of Creodonts. 



1838. IIij(vnndou Laizer & Parieu. Hysenodontidse. Oligocene France. 



1839. Pterodon Blainville. Hypenodontidse. Oligocene France. 



1841. Arcfoci/on Blainville. Arctocyonidii?. Basal Eocene France. 



1842. Palaeonictis Blainville. Palteonictida^. Lower Eocene France. 

 1862. Proviverra Riitimeyer. Hypenodontidte. Lower Eocene France. 



1870. Patriofclis Leidy. Oxy?enida». Middle Eocene, Wyoming. 



1871. S in o pa heidy. Hysenodontidse. INIiddle Eocene, Wyoming. 



1872. Stijpolophus Cope (= Sinopa). Hysnodontidie. Middle Eo- 

 cene, Wyoming. 



1872. Me.s-oni/.r Cope. ]Mesonychi(UTe. Middle Eocene, Wyoming. 



1872. Vivcrravus ]\Iarsh. ■Nliacidiie. Middle Eocene, Wyoming. 



1872. Uiniacyon Leidy. Miacid;ie. ]\Iiddle Eocene, Wyoming. 



1872. Limnocyon Marsh. Oxyjienidje. Middle Eocene, Wyoming. 



1872. Miaris Cope. Miacidje. Middle Eocene, Wyoming. 



1874. Oxyoena Cope. Oxyaenidjie. Lower Eocene, New Mexico. 



1874. Pachyania Cope. Mesonychidfe. Lower Eocene, New Mexico. 



1875. Didymidis Cope. Miacidae. Middle Eocene, Wyoming. 



1876. Dromocyon Marsh. ]\Iesonychid<^e. ]\Iiddle Eocene, Wyoming. 

 1881. Drltalhcrium Cope. Oxycljenidse. Basal Eocene, New Mexico. 

 1881. Dis.mcufi Cope. Mesonychidfe. Basal Eocene, New Mexico. 



1883. Cliriacus Cope. OxycljenidtTe. Basal Eocene, Wyoming. 



1884. Oxyclcenus Cope. Oxyclrenidfe. Basal Eocene, New Mexico. 

 Other American genera were later described by Scott, Osborn and Earl, 



Wortman, Matthew. European representatives, chiefly of the Oxyclsenidae 

 and Hyjenodontidpe, have been described by Filhol, Schlosser, Deperet 

 and others. Representatives of the Hycienodontida^ from the Fay Am of 

 Egypt have been described recently by Andrews (1903-6) and Osborn (1909). 



2. THE F I SSI P EDI A. 



1693. Ray divides the narrow clawed unguiculates into two' groups: 

 (1) those with several incisors in each jaw [/. e., the Carnivores], (2) those 

 "with one pair larger, of which kind all are plant eaters" [Rodentia]. Ray's 

 list of the former throws light on the origin of numerous technical and 



