27 



With this preliminary definition of the organic characters, 

 which appear to guide to a conception of the most natural 

 primary groups of the class MAMMALIA, I next proceed to 

 define the groups of secondary importance, or the subdivisions 

 of the foregoing subclasses. 



The Lyencephalous Mammalia are unguiculate : some 

 have the 'optic lobes' simple, others partly subdivided, or 

 complicated by accessory ganglions, the lobes being then 

 called 'bigeminal bodies.' 



The LYENCEPHALA with simple optic lobes are ' edentulous ' 

 or without calcified teeth, and are devoid of external ears, 

 scrotum, nipples, and marsupial pouch : they are true ' testi- 

 conda :' they have a coracoid bone extending from the 

 scapula to the sternum, and also an epicoracoid and epi- 

 sternum as in Lizards : they are unguiculate and pentadactyle, 

 with a supplementary tarsal bone supporting a perforated 

 spur in the male. The order so characterized is called 

 1 MONOTREMATA,' in reference to the single excretory and 

 generative outlet, which, however, is by no means peculiar to 

 them among Mammalia. It includes two genera Echidna 

 and Ornithorhynchus. Of the first, the species are terrestrial, 

 insectivorous, chiefly myrmecophagous, having the beak-like 

 slender jaws, and long cylindrical tongue of the true anteaters ; 

 but they are covered, like the hedgehog, with spines. Of the 

 second genus, the species are aquatic, with a flattened beak, 

 like that of a duck, which is used in the anserine manner to 

 extract insects and worms from the mud : but they are clothed 

 with a close fine fur like that of a mole, whence the name 

 * duck-mole' by which these anomalous quadrupeds are com- 

 monly known to the colonists. Both genera of Monotremes 

 are strictly limited to Australia and Tasmania. 



The LYENCEPHELA with divided optic lobes, forming the 

 'corpora bigemina' and 'quadrigemina' of anthropotomists, 

 have teeth, and with rare exceptions, the three kinds, viz. 

 incisors, canines, and molars. They are called MARSUPIA- 

 LIA, because they are distinguished by a peculiar pouch or 



