MAMMALIA. 8B 



The largest of these mammals are represented iu tlie Table-case 



Lower Eocene of New ]\Iexico, U.S.A., hy jaws which are 

 named Polymastodon in allusion to their " teeth with many 

 nipples." One piece of jaw and two plaster casts of com- 

 plete jaws are exhibited in Table-case 14a. A much smaller 

 Multituberculate, Ptilodus, occurs with Polymastodon in New 

 Mexico, while the allied Ncoplagiavlax (Fig. 78) is found in 

 the Lower Eocene of Elieims, France ; but there are no 



14a. 



Fio. 78. — Upper molar tooth of Neoplagimilax eocenus, grinding surface 

 and two lateral aspects, from the Lower Eocene of Rheims, France ; 

 the lower line indicating nat. size. (After Lemoine.) 



specimens of these in the collection. Nearly similar teetli 

 and jaws are met with in the Upper Cretaceous Laramie 

 Formation of North America ; and others, of the genus 

 Plagiaulax, of which several jaws are shown in the Beckles 

 Collection from the Purbeck Beds, have cutting teeth in 

 front and multituberculate teeth only ])ehiud (Fig. 79). 



Two-rooted multituljerculate teeth, belonging to an un- 

 Ivuown animal named Microlestes, are found even in tlie 



Fifi. 7"J. — Lower jaw and cutting teeth of Plagiaulax becMcsi, from the 

 Purbeck Beds of Swanage ; twice nat. size. (Table-case 14a.) 



Ithffitic Formation of England and Wiirtemberg. Specimens 

 of the very small M. moorei are exhibited from a Elia?tic 

 fissure-deposit at Holwell, near Frome. They bear tuliercles 

 round the edge of the crown and closely resemble the hinder 

 teeth of Plagicmlax. A skull with multituberculate teeth 

 from tlic Upper Triassic Karoo Formation of South Africa 

 was also placed here for some time. This (Fig. 81) was 

 descriljed under the name of Tntijlodon longsevvs and 

 assigned to a mammal by Owen ; while a fore limb from the 

 same formation, named Thcriodesimis 2'>hylarchus by Seeley, 



a 2 



