ALLOTHERIA. 641 



some observers they are placed with the Creodonta, to which they are 

 probably allied. All extinct, in the older Tertiaries of Patagonia. Bor- 

 hyaena, Prothylacinus, Amphiproviverra, etc., Ameghino. 



Sub-order 3. Allotheria. 



The Allotheria {MuUituherculata) are som3times treated as a separate 

 order of the ManunaUa, sometimes as a sub-order of the Marsupialia, and 

 sometimes as a sub-order of the Monotremata. The group is known to 

 us by very fragmentary remains, consisting of Uttle more than teeth, 

 sometimes the lower jaw, and in a few cases of parts of the skull and 

 small portions of other parts of the skeleton. They possess multituber- 

 culate molars with the tubercles arranged in two or three rows, and the 

 premolars are either similar or provided with a secant obliquely grooved 

 edge, not unhke those of certain Macropodidae. An important feature 

 of the dentition, and one wliich also recalls the diprotodont marsupials, 

 is the presence of a pair of large rodent-like incisors in the lower jaw 

 and of a pair of large incisors and sometimes of one or two pairs of smaller 

 incisors in the upper jaw. Canines are absent ; the lower jaw is without 

 the mylohyoid furrow, and its angle is inflected. In one form remains 

 of the scapula have been iound which suggest the presence of a distinct 

 coracoid. They have been found in a bed of marl a few inches tliick in the 

 Middle Purbeck (U. Jurassic) of Swanage, in the Jurassic of Wyoming, 

 U.S.A., and in the Laramie beds of the Upper Cretaceous of the same 

 country. Tritylodon, if it be a mimmal, is from the Trias of Stuttga»t 

 and of S. Africa, and Microlestes from the Trias of Bavaria. They also 

 extend into the lower Eocene of N. America and France. In the Laramie 

 formation hmb-bones have been foimd. which have been ascribed to this 

 group — pelvic bones not united, and a scapula with two facets, one of 

 which is supposed to have been for a coracoid (Camptomus). 



Fam. 1. Tritylodontidae. Premaxilla with a strong canine-Hke incisor 

 and a smaller incisor beliind, upper and lower premolars aUke, the latter 

 with three rows of tubercles. Trias of S. Africa and Eiu-ope ; by many 

 ragarded as reptiles. Tritylodon Ow., Karoo formation ; Triglyphua 

 Fraas, Trias of Stuttgart. 



Fam. 2. Bolodontidae. With two or three pairs of incisors in the 

 upper jaw ; upper premolars with three or four cusps. Jurassic, Creta- 

 ceous, Tertiaries. Bolodon Ow., Purbeck ; Allodon Marsh, Upper Jurassic 

 Wyoming ; Allacodon Marsh, Upper Cretaceous. 



Fam. 3. Plagiaulacidae. Lower jaw with one pair of large rodent- 

 hke incisors and inflected angle ; three or four cutting premolars marked 

 with oblique ridges on the outer face, and two small molars with tuber- 

 culated (crenulated) edges. Trias to Eocene. Microlestes PUeninger 

 {Hypsipryjnnopdis Dawldns), Upper Trias of Somerset and Wurtemburg. 

 Plagiaulax Falconer, Purbeck of Dorsetsliire. Ctenacodon Marsh, U. 

 Jurassic, Wyoming and several genera from the Laramie beds (U. Creta- 

 ceous) of N. America. Ptilodus Cope, L. Eocene of New Mexico and 

 Neoplagiaulax Lemoine, Lower Eocene of France. 



Fam. 4. Polyraastodontidae. Rather larger animals with a pair of 

 rodent-Uke incisors in the lower jaw, and tuber culated premolars and 

 molars. Lower Eocene of N. America, and teeth in the Laramie beds. 

 Polymastodon Cope. 



