TIIK MAMMALIA OF THE UINTA FOKMATION. 



550 



cation of Cope's table is 

 for brevity : 



A. — a. Carpals serial. 

 I. Taxkopkda. 



1. Priinilive. Pro t u ii gul a ta. 



c. Plantigrade. 

 e. Tarsals serial. 



b. Metapodials serial. 



2. I n t c r m e il i a t e. Condylar 



thra. 



c. Sulidigitigrade. 

 «. Tarsals serial. 



b. Metai)odiBls displaced. 



3. Recent. Ilyracoidea. 



c. Plantigrade. 



e. Tarsals serial or disi>laccd. 

 b. Metapodials displaced. 



l)i'oposed ; several subordiiial characters being omitted 



B. — a. Displacement of first upon sec- 

 ond rote of carpals not uniform. 



b. Metapodials displaced. 

 n. Amblypoda. 



c. Semi-planlisrade, plantigrade. 



d. Lunar upon cuneil'orm. 

 «. Astragalus upon cuboid. 



lir. PitOBOSCIDrA. 



e. Seuii-planligrade. 



d. Carpals serial, or lunar upon 



Inipezoid. 



e. Astragalus and na%'icular upon 



cuboid. 



IV. (MACnAUCHESIA.) 



c. Digit igriide. 



d. Scaphoid mid unciform upon 



magnum. 



e. Tarsals serial. 



C. — a. Displacement of first upon second 

 row of carpals uniform.* 

 b. Metapodials displaced, 

 e. Digili'jrade to unguligrade. 

 e. Tarsals more or less displaced. 



V. Dll'LAItrUKA. 



1. Pe rissod act y la. 

 /. Mcsaxonic. 

 e. Carpal disidaccnient extreme in 



reduced forms. 

 e. .Vstragalo-cuhoidal lacet Hat. 

 3. A r t i o d a <U y 1 a. 

 /. Paraxon i(;. 

 a. Carpal displacement limited in 



reduced Ibrms. 

 e. Astragalo cuboidal facet gingly- 

 moid. 



The position of the To.vodontia and of Macrauchenia is doubtful. 



The three subdivisions above employed (A, B, C) bring out what appeals to l)e 

 a fundamental distinction between Orders IF, III, IV and V. The significance of 

 the diverse carpal displacement in the Artiodaetyla and Perissodactyla is shown in 

 the next section. 



V. T[IK TRINCIPLES OF DTSPLACEMKNT. 



The evolution of llic luamis and pes ol' the iiiiL-iilatL's inrliidLMl llic I'uliouiiiir 

 proces.ses : (I) Elevation fioin tiu' [)lantigrade to the digitigrade position ; (2) 

 growth of certain tlcments and icd ii e t i o ii of otiiers, including the loss of lat- 

 eral parts ; (3) d i - p 1 a c c iiic ii I of I lie elements of the podium and inefapodium from 

 the primitive .serial arrangement; (4) coalescence of parts primitively distinct. 

 All these processes interacted upon each other, and so far as they can be distinguished, 

 took place, for the most part, in the order named. That is, elevation usually preceded 

 the metatroj)hic or unequal growth of parts and the elongation or vertical growth of 

 the ineta|todi;il elements involved the mutual displacement or iiiterloeking of the 

 podials and metapodials. The etlects ofthe.se proces.ses were in the nature of adapta- 

 tions correlated with changes in the entire body which were induced by the habitat, 

 manner of feeding, character of the ground, necessity of speed liotli in ranging for 



*Scc this Memoir, p. .">ll. Tlic scaplio-magnum = lunar-cuneiform fiicet. 



