Revietos — Prof. Cope's Extinct Vertebrates of N. America. 473 



late groups, from the characters of their upper molar dentition. The 

 first is equivalent to Owen's Sarcophaga ; and among it may be men- 

 tioned the European and North American Eocene genus Feratlierium, 

 which Prof. Gaudry identifies with Didelphys. The second group 

 agrees with Owen's Poephaga, and is unrepresented in the Tertiaries 

 of North America. The Multituberculata is divided into the Trity- 

 lodontidse, represented by the Mesozoic Stereognnthiis of Europe and 

 Tritylodon of South Africa ; the Polymastodontidee, represented by 

 the American Eocene Polymastodon ; and the Plagiaulacidse, repre- 

 sented by the European Mesozoic Plagiaulax and the Eocene Neo- 

 plagiaulax. A genealogical table is given on page 695, in which it 

 is sought to derive ThylacoJeo thi'ough Plagiaidax from Tritylodon ; 

 but it appears to us that the peculiar structure of the characteristic 

 tooth of Plagiaulax and its extremely small size must be an effectual 

 bar to this view. 



The Amblypoda. — We have already given our opinion in favour of 

 regarding this so-called order as a suborder of the Ungulata ; it is 

 divided into the sections Taligrada, Pantodonta, and Dinocerata. The 

 first is represented by the single genus Pantolambda, characterized by 

 the presence of a " head " to the astragalus. The second (for which we 

 should prefer the nameCoryphodontia) includes the widely-distributed 

 Conjphodon Estacodon, Metalophodon, Bathmodon, etc. ; and is charac- 

 terized by the presence of a third trochanter to the femur — a feature 

 by which it is much more closely related to the Perissodactyla than 

 the third section, in which it is absent. The latter section having 

 been fully noticed in this Magazine, in a review of Prof. Marsh's 

 Dinocerata, does not call for further reference on this occasion ; a 

 number of figures of Loxophodon occur in it. 



Permian Batrachia. — Having already exceeded the space we had 

 originally assigned to this notice, we must pass the present memoir 

 with the briefest reference. It contains descriptions of several forms 

 belonging to the group called by Prof. Cope the Ehachitomi, but 

 which we think might be more advantageously known as the Arche- 

 gosauria ; it being in our opinion far preferable to take group-names 

 from the genera which have been the longest established and are the 

 best known. The peculiar structure of the vertebral column in this 

 group is ingeniously illustrated by the folds caused by flexure in the 

 sleeve of a coat. Figures are given of the crania of Trimerorhachis, 

 Eryops, and Cricotus ; all of which appear to be peculiar to America. 

 That this group had originally a very wide extension in space is 

 proved by the occurrence of representatives in the Permian of 

 Europe (Actinodon and Archegosaurus), in the Karoo system of South 

 Africa (Rhytidosteus) , and in the Gondwana system of India {Gond- 

 loanosaurus). All the members of the group are characterized by 

 the imperfect ossification of the centra of the vertebral cohunn ; each 

 of which consists of two lateral moieties, an azygos basal moiety, 

 and in some cases of a fourth element corresponding to the " wedge- 

 bone " of the Bhynchocephalia. 



In the foregoing notice we have not spai'ed adverse criticism where 

 we thought there was cause for the same, and we venture to think 



