1080 The Artiodactyla. 
II. Superior molars quadritubercular with an intermediate 
fifth. 
1. Three digits (Anoplotheroidea). 
Intermediate tubercle anterior Anoplotheriide. 
11. Two or four digits (Anthracotheroidea). 
A, The intermediate tubercle posterior. 
Four digits; molars bunodont si.s. ossis deseris iisen Dichobunide. 
Four digits; molars selenodont ...... Ceenotheriide. 
AA, The intermediate tubercle anterior. 
Four digits ; one series of V’s below acotheriide. 
Two or four digits; two series of V’s below ......... Xiphodontide. 
III. Superior molars quadritubercular, without an interme- 
diate fifth. 
A, Molars bunodont, or cross-crested, (Suoidea). . 
Mandibular condyle triangular ; no postglenoid process ...... Suide. 
Mandibular condyle subcylindric ; a postglenoid 
process ue Hippopotamide. 
AA, Molars selenodont (with four crescents above). 
a. Inferior molars with one series of crescents (Meryco- 
otamoidea). 
Premiolare tislike molditts, cei hi aie Merycopotamide. 
aa. Inferior molars with two series of crescents. 
8. Superior premolars (except first premolar) with one 
crest (Cameloidea). 
y. “Fourth premolar like molars below, with three 
crests above.” : 
Two digits only (four? in Agriocheerus)...... esessees Dichodontide. 
yr. Fourth premolar entirely different from molars. 
ð. Navicular and cuboid bones distinct from each other. 
e. Superior incisors present. 
A iT 
No cannon bone; a vertebrarterial canal ...........--- Oreodontide. 
No vertebrarterial canal; no cannon bone .....-.++ Poébrotheriide. 
No vertebrarterial canal; a cannon bone; .....+-++++ Pro 
es. No superior incisors (except incisor three). — 
No vertebrarterial canal; a cannon bone; superior p. m. IV with 
external and internal crests ..........sss0+eeeeenenereeee® Camelidæ. 
Like Camelidæ, but superior p. m. iv a simple cone ... Eschatiide. 
3 66. Navicular and cuboid bones codssified. 3 
