Gregory: notharctus, an American eocene primate 



171 



head as seen from above. On the neck of the malleus opposite the lower part of the articular facet is 

 an osseous lamina, the base of the processus longus, which has been torn off. Behind the lamina on the 

 inner or cranial aspect of the neck is a deep fossa. All this is essentially the same as in Lemur and Pro- 

 pithecus save that the fossa is deeper and the vertex of the head is not elevated. The manubrium is 

 somewhat crushed but appears to be complete; it differs from that of all other Primates in being extremely 

 short in proportion to the width of the neck ; it was wider at the base than in Propithecus and more sharply 

 bent upon the neck, as it is in Lemur. The processus brevis and processus muscularis were not recognized. 



The incus much resembles that of Propithecus in the general form of the body and in the shape of 

 the articular surface; it differs in its smaller size, in the shortness of both its processes and in their wide 

 divergence from each other. The tip of the stapedial process (proc. longus) as preserved is pointed, an 

 unusual character, which at first suggested that this pointed process was the processus brevis; but further 

 comparison of the articular surface and the general form of all the parts confirmed the present interpre- 

 tation. No trace was found of the os orbiculare, or lenticular disc, on the end of the stapedial process 

 of the incus. 



The neck and crura of the stapes were found in situ, surrounding the bony stapedial canal as in Pro- 

 pithecus and Lemur. The foot plate, however, was not found. The stapes was unfortunately lost after 

 being successfully extracted from the matrix, but not before it was compared with the stapes of Pro- 

 pithecus and Lndris,^ with which it agreed in general characters. The crura were delicate in their middle 

 part, but the neck was broad as in Indris. 



Accordingly, the ossicles of Notharctus appear to be of a primitive lemuriform character, the malleus 

 being somewhat coarser than that of Propithecus with heavier head and articular facets and probably 

 with a stouter lamina and processus longus, the manubrium being extremely short and more bent upon 

 the head. 



A REVIEW OF THE COURSE OF THE INTERNAL CAROTID ARTERY AND OF ITS BRANCHES IN THE 

 15ASICRANIAL REGION OF PRIMATES - 



The consideration of the foramina in the region of the auditory bulla of Notharctus has led to a general 

 review of the course of the internal carotid artery and its branches in the primates, with special reference 

 to the foramina which serve for the entrance and exit of these and other arteries. This subject has been 

 treated by a number of authors, especially Mivart (1864), Winge (1895), Tandler (1899, 1901, 1902), 

 Wortman (1903), van Kampen (1905), Stehlin (1912, pp. 1206, 1207, 1212), and Keibel and Mall (1912, 

 II), whose observations and chief conclusions are considered below. 



Insectivora 

 Text Fig. 65 



In Erinaceus, according to the researches of Hyrtl, Tandler (1899, p. 749) and others (cf. van Kampen, 

 p. 430), the internal carotid enters the bulla from the rear, through a foramen that is incompletely sepa- 

 rated from the stylomastoid foramen. Inside the bulla the artery divides into the arteria stapedia and 

 the art. pro7nontorii, as in lemurs. The art. stapedia is of large size, and after piercing the stapes runs 



1 Cf. Milne Edwards and Grandidier, 1875, PI. lxxxv, fig. 10. 



2 A summary of the following section was presented before the Paleontological Society of America, December 31, 1914, and pub- 

 lished in 191.5. Bull. Geol. Soc. America, XXVI, pp. 426-432. 



