1910.] The Allotheria, or M ultituberculata 165 



1855. Charlesworth describes a fragmentary lower jaw, Stcreognathus, 



odlithieus from the Stonesfielcl Slate (Middle Jurassic). 

 1857. Falconer describes the mandible and teeth of Plagiau/ax from the 



Purbeck (Upper Jurassic). 

 1864. Dawkins describes the grooved premolar of a relative of Plagiaiilax 



(H i/psiprymnopsis) from the Rhtetic of Somersetshire, England. 

 18(5(3. ]Murray erects for Stereognathus the family Stereognathida". 

 1866. Fraas describes a tooth with three rows of cusps from the Rhsetic 



and proposes the name Trigli/phus. 

 1871. Owen monographs the Mesozoic Mammalia and treats the genera 



Microlestes, P/agiaulax, and Stereognathus as a division of the 



Diprotodont Marsupials. 



1871. Owen proposes the name Bolodon for some upper jaw fragments. 



1872. Gill proposes the family name Plagiaulacidse. 



1879. INIarsh describes some small jaws and teeth (Ctenarodon) from the 

 Upper Jurassic (" Atlantosaurus Beds") of Wyoming. 



1880. ]Marsh erects the order Allotheria to include '' Plagiaulax, the allied 

 genus Ctenacodon, and possibly one or two other genera." 



1881. 1882. Cope describes PtUodus (1881) and Pohjmastodon (1882) from 



the Basal Eocene of New Mexico. 



1882. Cope describes Meniscoessus from the Laramie (Upper Cretaceous) 

 of Wyoming. 



1882. Lemoine describes NeopJagiauJax from the Basal Eocene near 



Rheims, France. 

 1884. Owen describes the front part of a skull with teeth, named Tritylodon 



from the Upper Triassic of South /Africa. 

 1884. Cope uses the name " Multituberculata " as a suborder of the 



Marsupialia, to include the Tritylodontidf^e, Polymastodontidae and 



Plagiaulacidfe. 



"Multituberculata" is thus virtually a synonym of Allotheria Marsh. 

 1884. Cope in his 'Tertiary Vertebrata' gives evidence of the Marsupial 



nature of Pohjmastodon (CafopsaJis). 



1887. Cope erects the family Chirogidse. 



1888. Osborn revises the group, dividing it into the families Plagiaulacidae, 

 Bolodontida", Tritylodontidse and Polymastodontidse. 



1903. Ameghino includes in the group the Patagonian families Polydolo- 

 pidse Ameghino (1897) and Promysopidse Ameghino. These 

 however may prove to be highly modified Csenolestoids (p. 211). 



1909. Gidley describes a skull and lower jaws of PtUodus (all previously 

 known skull material had been very im])erfect), shows that this 

 genus possesses many characteristically INIarsupial features, and 



