194 



NA TURE 



\_Dcc. 31, 1885 



genera and species, and as such is an extensive and in- 

 valuable mine of information, wherein paleontologists 

 may work with profit for many years to come. But 

 besides the more special descriptions, there is much of 

 deep interest to the naturalist and evolutionist, a flood of 

 light being thrown on the early Eocene forms, which 

 were probably the progenitors of our existing mammals. 



The Saurian genus Chainpsosaurus, hitherto known 

 only from Cretaceous deposits, has now been found in 

 the Puerco Tertiary series. The remarkable marsupial 

 genus Plagiaulax, was originally described by Falconer 

 from British Purbeck beds ; within the last few years an 

 almost identical genus has been met with in Tertiary 

 strata in France ; and now closely allied forms are made 

 known to us from the American Tertiary groups. It is, 

 however, among the higher mammalia that the most 

 remarkable discoveries have been made. The finding of 

 forms, less specialised than those living at the present 

 day, has enabled Prof. Cope to trace what he believes to 

 be the line of descent of some of the groups of living 

 mammals. The determination of the characters of a 

 considerable number of new genera and species, more or 

 less closely allied to the Inscctivora, has led to a new 

 classification. It is proposed to include in a new order, 

 called the Bitnotheria, the sub-orders : — (i) Creodoitta, 

 (2) Mcsodonta, (3) Inscctivora, (4) Tillodonta, (5) Tain'o- 

 donta, and (5) Prosimice ? The Creodoitta come nearest 

 to the Carnivora, while the Prosimio: come nearer to the 

 Qiiadnimana, groups (4) and (5) being distinguished by 

 the possession of incisor teeth with persistent pulps. It 

 is among the Eocene Creodoitta that Prof. Cope finds the 

 ancestors of the Felida- and Canida. " In distinguishing 

 between the ancestors of the Felida: and Canidce, we 

 naturally seek to recognise in each an anticipation of the 

 leading characters in the dentition which distinguish 

 those families to-day" (p. 263). In the Felida; we should 

 expect a gradua/ abbreviation of the true molar series 

 from behind. The Caiiido', on the other hand, not only 

 retain the true molars, but have them also of a tubercular 

 character. " Estimated by these tests the Myacida are 

 clearly the forerunners of the Canida, and the O.xyanidu: oi 

 the Felida." The following diagram will show the families 

 through which these relations are traced (p. 264) : — 



Felidce 

 \ 

 Felidae 

 \ 

 Oxysena 



CanidiE 



I 

 CanifUi: 



I 

 Myacidie 



Oxyaenidse 

 \ 

 Leptictida; 



Hyrenodontids: 

 / 

 / 

 / 

 Mfsonycliida; 



Amblyctonidse 



Unfortunately the new names prevent our fully appre- 

 ciating these affinities, which can only be properly under- 

 stood when the characters of these groups have been 

 carefully studied. The forms allied to Caiiis which have 

 been met with in the Lower and Middle Miocene are all 

 said to be generically distinct from Caiiis, while those 

 from the Upper Miocene pertain to the same genus The 

 many new species of Carnivora have suggested to Prof. 

 Cope a new grouping for the Fissipedia. These are in 

 the first place divided into two subdivisions :— 



(i) " External nostril occupied by the complex maxillo- 



turbinal bone ; ethmoturbinals confined to the posterior 

 part of the nasal fossa ; the inferior ethmoturbinal of re- 

 duced size . . . Hy polity ceteri. 



(2) " External nostril occupied by the inferior ethmo- 

 turbinal and the reduced maxilloturbinal .... Epimy- 

 ceteri." 



No. I includes the families Cercoleptidce, Procyoitida, 

 Miistelidce, jElitridce, Ursidce, Canida:. 



No. 2 the Proielidce, Arctictidce, ViverridcB, Cynictidce, 

 Siiricatidce, Cryptoproctida, Nimravida, Felidce, Hycsii- 

 idce. 



The species of Carnivora described are from the Mio- 

 cene, and are all referable to the Ca/tidte and NimravidcE, 

 the first being divided into eight genera, all of which are 

 represented except Ca/iis ; they have much resemblance 

 to our dogs and foxes, and are separated chiefly by the 

 modifications of their teeth. The second includes nine 

 extinct genera, all closely allied to the Felidce, but differ- 

 ing in having an alisphaenoid canal and post-glenoid fora- 

 men. In some of them the dental formula is the same as 

 that of the Felidce; but in others there is an increase in 

 the number of the molars and premolars. It is these 

 variations which are used as generic distinctions. Some 

 of the genera, such as Pogonodoii, have the canine teeth 

 so largely developed as to make a near approach to the 

 sabre-toothed tigers. 



The changes which are proposed in the names and 

 grouping of the herbivorous animals are not less nume- 

 rous or less radical than those among the flesh-eaters, to 

 which allusion has been made above. The order Ungu- 

 lata, as it is now generally understood, is to be divided 

 into four orders, founded on characters of the carpus and 

 tarsus ; these are as follows : — 



(i) Taxeopoda (including sub-orders Hyracoidea, Con- 

 dylarthra, and Toxodontia ?). 



(2) Proboscidea. 



(3) Amblypoda (including Pantodonta, Dinocerata, and 

 Talligrada). 



(4) Diplarthra (including Perissodactyla and Artio- 

 dactylci). 



The necessity for some modification of this classifica- 

 tion is already pointed out by Prof. Cope himself, for on 

 p. 383, in speaking of the almost perfect skeletons of 

 P/ienacodus primcevus and P. Vortmani, which genus is 

 placed in t\ie Condylarihra (Order l), he says: — "The 

 unexpected result is, that this genus must be placed in 

 a special group of an order which includes also the 

 Proboscidea." 



Not the least important outcome of these discoveries 

 in the Eocene deposits is the reconstruction, from nume- 

 rous specimens, of the genus Hyracotherium ; and con- 

 sequent upon this the knowledge that it is, as Prof Cope 

 thinks, the earliest ancestor of the Perissodactyla. The 

 following genealogical tree will show this relationship 

 (p. 617) :- 



Equidze 



Rhinocerida^ 



Hyiacodonlidje 



\. / 



Triplopidse / 



Lophiodontida; 



\ / 



HyiacotlierinK 



Palffiotherida- 

 / 

 Tapirida; / 



\ Menodontida: 



\/ 

 Chalicotheridse 



