GREGORY: XOTHARCTUS, AN AMERICAN EOCENE PRIMATE 



155 



Nasals 

 Text P^igs. 52, 54 



The nasals of N^otharctus venticolus and .V. osborni spread at the proximal end, where they have wide 

 contacts with the frontal and maxillary; they are decurved and taper toward the distal end, where each 

 ends in a short pointed tip. In A'', crassus the distal end seems to have been heavier than in the others. 

 In Adapts magnus (Stehlin, 1912, pp. 1248, 1249, figs. 275, 276) , on the other hand, the nasals are narrow prox- 

 imally and swell more or less widely toward the distal end. Even the primitive Adapis magnus var. leen- 

 hardti (Stehlin, 1912, p. 1278, fig. 286) shows a beginning of this tendency, but in .4. parisiensis it is less 

 pronounced, the proximal ends in the variety bruni (Stehlin, 1912, p. 1192) approaching the conditions 

 in Nothardus; the distal end, however, is wider. The inferior border of the proximal part of the nasal 

 in A^. venticolus (Amer. AIus. No. 14656), where it meets the ascending plate of the maxilla, was produced 

 inward as a prominent crest. 



Maxilla; 

 Text Figs. 49, 58 



In Nothardus the maxillary is essentially similar to that of Adapis but appears to be somewhat 

 longer anteroposteriorly that of Adapis tending to become short and deep. The posterosuperior extension 

 of the maxillary is in contact with the frontal and the lacrymal as in Adapis. A shallow fossa on the side 

 of the maxilla in front of the lacrymal is present also in Adapis and probably lodged the orbicularis pal- 

 pebrarum muscle (Stehlin) . The infraorbital canal and foramen are best seen in a young fragmentary 

 skull of A^. osborni (Amer. Mus. No. 12569); the foramen is about two millimeters in height; it opens 

 about four millimeters above the anterior end of p\ Stehlin's figures (pp. 1196, 1197, 1251) show that in 

 Adapis the infraorbital foramen was sometimes double and opened above p* or between p'* and p^. The 

 tubercle for the anterior tendon of the masseter is located on the maxilla immediately below the junction 

 with the malar as in Adapis. (Fig. 58.) The palatal shelves of the maxillae are long and narrow 

 transversely. There is considerable variation in the relative width of these elements in different forms 

 of Adapis as shown in StehUn's reconstructions. (Figs. 59-61.) 



Lacrymals 

 Text Figs. 49, 51, .52 



This element is preserved in Nothardus tenebrosus (?) Yale Aluseum, No. 12151; its relations with 

 surrounding elements are partly indicated in A'', venticolus, American Aluseum No. 14656, and in A^. osborni 

 No. 11466). It formed a prominent protuberance on the extreme anterior limit of the orbit above 

 the anteroinferior orbital rim (crista anterior), which was formed by the malar. The lacrymal did not 

 extend in front of this rim, at least as seen from the outside, and hence there was no exposed pars facialis. 

 The lacrymal foramen was located at the extreme anterior corner of the lacrymal and immediately 

 behind the upper part of the crista anterior. The foramen may have been partly surrounded by the 

 lacrymal, partly by the maxilla and perhaps partly by the jugal; at least it lies at or very near the meet- 

 ing place of these elements. The Umits of the orbital part of the lacrymal are not shown. The protu- 

 berant portion (crista posterior) articulated above with the frontal. It was separated from the nasal 

 by the fronto-maxillaiy contact. The upper part of the crista anterior near the foramen may have 

 been formed exclusively by the maxilla rather than by the lacrymal, and if this is true then the malar 

 did not quite reach to the lacrymal. But at most there was only a narrow strip formed by the maxilla 

 between the malar and the lacrymal. 



