248 W. K. GREGORY TUPAIID.E AND EOCENE IEMURS 



and the Leniuridae in the structure of the male reproductive organs and 

 in the abdominal musculature. Quite recently Dr. Elliot Smith, 4 accept- 

 ing the theory that the Tupaiidae show us what the ancestors of the 

 Primates were like, says that they also illustrate the influence of an 

 arboreal mode of life in stimulating, first, a great development of the 

 centers of sight, sound, touch, and muscular sensibility ; and, secondly, an 

 arrest in the development of the olfactory centers, which are predominant 

 in terrestrial Insectivores. 



Tupaiid Osteology and Eelatioxships 



The opportunity of studying the skeleton of Ptilocercus has led me to 

 review the general subject of Tupaiid relationships. This phylogenetic 

 problem may be stated as follows : Are the special resemblances between 

 Tupaiids and Lemurs due largely to convergent evolution between widely 

 removed phyla ? Or are they due partly to homoplastic evolution in re- 

 lated phyla, which have been derived from a single family of Mesozoie 

 Insectivores ? 



Some of the more important characters tending to ally Tupaiids and 

 Primates are as follows : 5 The brain and brain-case of Tupaiids are far 

 larger than in typical Insectivores ; the eyes and orbits are large : the 

 olfactory portions of the skull more or less reduced (especially in Ptilo- 

 cercus) ; the orbits are inclosed posteriorly by a postorbital bar ; the 

 prominent malar is pierced by a foramen below the orbits, as in Lemurs : 

 the malleus, incus, and stapes, according to Doran. in several features 

 much resemble the Lemur and ceboid types ; the large auditory bullae arc 

 formed from the inflation of the entotympanic, the true or eetotympanic 

 remaining as a bony ring, as in non-Malagasy lemuroids (van Kampen). 

 The same authority notes the agreement in the course of the entocarotid 

 artery with that of Lemuridse, and further agreements are seen in the 

 arrangement of the pterygoid region. Tupaia is stated to have a lemur- 

 like sublingua : the abdominal musculature and male reproductive organs. 

 as already stated, point in the same direction. The sternum, girdles, 

 and all the limb bones, the hand and foot with the divergent pollex and 

 hallux, the tarsus, especially the astragalus, offer additional evidence of 

 relationship. Finally, in Tupaia there are twelve or thirteen dorsals, six 

 or seven lumbars, and three sacrals, exactly as in certain Lemurs. 



I think this body of evidence is sufficient to indicate that even although 

 Tupaiids and Lemuroids may have separated very early, and even al- 



* Address to the Anthropological Section. Brit. Assoc. Adv. Sci., Section A. Dundee, 

 1912, pp. 1-24. 

 •Gregory; Op. cit., pp. 321-322. 



