CHAP. VII.] MAMMALIA OF THE NEW WORLD. 133 



belong to the rrimates; so that no less than twelve genera of these 

 animals are recognized by Mr. INIarsh, who classes them in two 

 families — Limnotlieridte, comprising the genera Limnotherium, 

 (which had larger canine teeth), Thinolcstcs, Tclmatolcstes, Mesa- 

 codon, Bathrodon, and Antiacodon of Marsh, w^ith JSfotharctos, 

 Hipposij^is, Microsyops, and Falcvacodon previously described by 

 Leidy ;— and Lemuravidiie, consisting of the genera Zemuravus 

 (Marsh) and Hyopsodus (Leidy). The animals of the latter 

 family were most allied to existing lemurs, but were a more 

 generalized form, Lcmuravus having forty-four teeth, the greatest 

 number 'known in the order. These numerous forms ranged from 

 the size of a small squirrel to that of a racoon. It is especially 

 interesting to find these peculiar lemuroid forms in America, 

 just when a lemur has been discovered of about the same age 

 in Europe ; and as the American forms are said to show an 

 affinity with the South American marmosets, w^hile the European 

 animal is most allied to a West African group, w^e have 

 evidently not yet got back far enough to find the primeval 

 or ancestral type from which all the Primates sprang. 



About the same time, in the succeeding Miocene formation, 

 true monkeys were discovered. Mr. Marsh describes Laopithe- 

 CHS as an animal nearly the size of the largest South American 

 monkeys, and allied both to the Cebidte and the Eocene Limno- 

 theridae. Mr. Cope has described Mcnothcrium from the Mio- 

 cene of Colorado, as a lemuroid animal, the size of a cat, and 

 perhaps allied to Limnothcriurn. More Miocene remains will, 

 no doubt, be discovered, by which we shall be enabled to trace 

 the origin of some of the existing forms of South American 

 monkeys ; and perhaps help to decide the question (now in dis- 

 pute among anatomists) whether the lemurs are really Primates, 

 or form an altogether distinct and isolated order of mammalia. 



Insedivora. — This order is represented by comparatively few 

 forms in the tertiary beds, and these are all very different from 

 existing types. In the Upper Miocene of Dakota are found 

 remains indicating two extinct genera, Le2yictis and Ictops. In 

 the Miocene of Colorado, Professor Cope has recently discovered 

 four new genera, Isacis ; allied to the preceding, but as large as a 



