2
MAMMALIA.
following table : these characters are not always those of the greatest importance, but only those most easily recognized:—
Subclass EUTHERIA.
| A. |
Posterior limbs present.
|
| a. |
Animal not modified for flight.
|
| a'. |
Incisors present in one or both jaws.
|
| a''. |
Incisors in front of the upper and lower jaw, either not two in number or not chisel-shaped.
|
| a3. |
Feet terminating in distinct toes with claws or nails.
|
| a4. |
Hallux or pollex or both opposable to other digits.
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|
1. PRIMATES. |
| b4. |
Neither hallux nor pollex opposable.
|
| aa. |
Upper lip in general not projecting far beyond
lower; median pair smaller than other incisors
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|
2. CARNIVORA. |
| bb. |
Snout very pointed; upper lip projecting far beyond lower;
median pair of incisors generally larger than the others
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|
3. INSECTIVORA. |
| b3. |
Feet either not terminating in distinct toes or furnished with hoofs or hoof-shaped nails
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|
6. UNGULATA. |
| b''. |
Two chisel-shaped incisors in front of each jaw
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|
5. RODENTIA. |
| b'. |
No incisors, except in certain Armadillos; Indian forms toothless
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|
9. EDENTATA. |
| b. |
Animal modified for flight; fingers enormously developed to support a membranous wing
|
4. CHIROPTERA. |
| B. |
No external posterior limbs: body modified for swimming.
|
| a. |
Homodont or toothless: breathing-orifice generally on top of head; a back fin in most genera; mammæ inguinal
|
7. CETACEA. |
| b. |
Indian form heterodont: breathing-orifice at end of muzzle; no back fin; mammæ pectoral
|
8. SIRENIA. |
