PHYLOGENY. 127 



I. A large coracoid bone articulating with the sternum. An inter- 

 clavicle (Prototheria). 



Epicoracoid and marsupial bones ; fibula articulating 

 with proximal end of astragalus : i. Monotremata. 



II. Coracoid a small process coossified with the scapula (Eutheria). 



a. Marsupial bones ; palate with perforations (uterus divided ; 

 placenta and corpus callosum rudimental or wanting ; cere- 

 bral hemispheres small and generally smooth). 



But one deciduous molar tooth : 2. Marsupialia 



aa. No marsupial bones ; palate generally entire (placenta and 



corpus callosum well developed). 



f3. Anterior limb reduced to more or less inflexible paddles 

 posterior limbs wanting (Mutilata). 



Elbow-joint fixed ; carpals discoid, and with the digits 



separated by cartilage ; lower jaw without ascending 



ram us : 3. Cetacea. 



Elbow-joint flexible ; carpals and phalanges with normal 



articulations ; lower jaw with ascending ramus : 



4. Sirenia. 

 ft(3. Anterior limbs with flexible joints. Ungual phalanges 



compressed and pointed 1 (Unguiculata). 

 7. Feet taxeopodous (with exceptions in the carpus). 

 J. Teeth without enamel ; generally no incisors. 



Limbs not volant ; hemispheres small, smooth : 



5. Edentata 

 66. Teeth with enamel ; incisors generally present. 



No postglenoid process ; mandibular condyle not trans- 

 verse ; limbs not volant ; hemispheres small, smooth : 



6. G lire s 

 Anterior limbs volant ; hemispheres small, smooth : 



7. Chiroptera 



A postglenoid process ; mandibular condyle transverse ; 

 limbs not volant; no scapholunar bone 2 ; hemi- 

 spheres small, smooth : 8. Bunotheria? 

 A postglenoid process ; limbs not volant, with a scapho- 

 lunar bone ; hemispheres larger, convoluted : , 



9. Carnivora. 



1 Except Mesonychiidae. 



2 Except Erinaceus and Talpa. 



3 With the suborders Pantotheria, Creodonta, Insectivora, and Tillodonta 



