ORDER PRIMATES. 



I465 



such as the Insectivora. In the case of fossil forms it appears, in- 

 deed, that the Lemuroids can only be distinguished from the Insec- 

 tivores by the absence of the cleft in the terminal phalangeals of the 

 digits, so that when these are unknown it is frequently very difficult, 

 if not impossible, to determine to which order such forms should be 

 referred. Since, moreover, as we have stated under the head of the 

 Insectivora, it is probable that Insectivores and Lemuroids are de- 

 scended from the same ancestral stock we must expect to find the 

 characters common to the two groups increasing in importance and 

 number as we recede in time. By Professor Cope the Lemuroids 

 are, however, regarded as closely allied to the Condylarthrous Un- 

 gulates ; and that writer proposes to brigade together the Primates, 

 Condylarthra, and Hyracoidea under the common name of Taxeo- 

 poda ; the Condylarthra being regarded as the ancestral type. Xow 

 although we may be prepared to admit the derivation of the Condly- 

 arthra from the common stock which gave origin to the Insectivora 

 and Primates (see p. 1455), yet the apparent absence of clavicles in 

 all the known representatives of that group renders it at least pre- 

 mature to say definitely that it gave rise to the Primates. At the 

 present day Lemuroids are confined to the warmer regions of the 

 Old World, being especially characteristic of Madagascar and certain 

 parts of Africa. The recent forms are divided into the families 

 Lemuridtf, TarsiidcB, and Chiromyidts. 



Family Hyopsodoxtid.e. — This family name was proposed by 

 Dr Schlosser 1 for the reception of certain North American Eocene 

 forms now looked upon by most writers as undoubted Lemuroids, 

 although some of them have been classed among the Insectivora. 

 The most generalised form is Pelycodus, from the Eocene of New 

 Mexico, at one time regarded by Pro- 

 fessor Cope as an Insectivore allied to 

 Tupaia. Dr Schlosser states that it pre- 

 sents some affinity to the Insectivorous 

 JMicrochivrus, which he places in the same 

 family. Hyopsodus (fig. 1348), of the 

 American Eocene, has the dental formula 



C. -, Pm. 



Fig. 1348. — Palatal view of the 

 left upper (a) and lower (£) dentition 

 of Hyopsodus vicarius ; from the 

 Eocene of North America. (After 

 Cope.) 



-, M. - : the third upper 

 2' i' 4 3' 



premolar is as well developed as the 

 second, by which character it is readily 

 distinguished from Microchcerus, to which 

 it has been compared. Several species have been described, of 

 which one comes from the Lower or Puerco Eocene, while the others 

 are from the higher Wasatch and Bridger horizons. Microsyops is 



1 Wrongly given as Hyopsodid<2. 



