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



and of the lack of evidence for placing them in either of the mammalian 

 subclasses it seems advisable to treat them provisionally as representing a 

 transitional group to which the name "Promammalia" of Haeckel may 

 conveniently be applied. 



Definitions. 



Class Mammalia. Condylar process of dentary articulating with the squamosal. 



Quadrato-articular joint with squamosal much reduced 

 or (usually) absent. Lower molars with at least two incipient 

 fangs. 

 Sub-class Promammalia Haeckel. (Hypothetical definition). Quadrato- artic- 

 ular joint much reduced but still retaining its primary func- 

 tion in part. Oviparous; integument retaining some scales 

 mingled with the hairs. (Compare the definition of Proto- 

 theria, p. 230.) 

 Order Protodonta Osborn. Dentary the main functional element of the 

 lower jaw. Corono-condylar region very broad. Corono- 

 condylar sinus shallow. Lower molars with two incompletely 

 separated fangs, a single pointed main cusp and small ante- 

 rior and posterior cusps. Talonid spur incipient. Premolars 

 styliform. 

 Family Dromatheriidse. 



Genus Tribolodon Seely. No angular process, molars with larger 

 anterior and posterior cusps, but division of fangs only be- 

 ginning. (Possibly a Cynodont). 



Genus Dromatherium Osborn. Lower incisors three, styliform, 

 erect, arranged in a decreasing series which descends anteri- 

 orly uj)on the symphysis, the upper incisors probably over- 

 hanging the lower in a similar descending series. Canine 

 piercing, recurved. P 4, M 6. No angular process. Oppo- 

 site rami weakly conjoined at symphysis ? Pj-pa pro- 

 cumbent. 



Genus Microconodon Osborn. A small angular process, exca- 

 vated on the internal face as if embracing a separate angular 

 bone. Molar crowns lower, with anterior and posterior 

 cusps better developed than in Dromatherium. A well 

 marked depression between the anterior and posterior fangs. 

 Symphyseal region stout. Third lower premolar with inci- 

 pient fangs, premolars erect. 



The Allotheeia, or INIultituberculata. 



Historical developmcyjt of the ordinal cIassificatio7i.^ 



1847. Plieninger describes the single lower molar of Microle.stes antiquus 

 from the Iveuper (Upper Trias near Wiirttemburg). 



Compiled chiefly from Palmer's "Index Generum Mammalium.' 



