1 6 THE OSTEOLOGY OF THE REPTILES 



(Fig. S3) and Therapsida (Figs. 43, 44, 45), and all other reptiles, they 

 are excluded from the narial margin. They are small or vestigial in 

 the Squamata, and absent in most Chelonia and in Sphenodon (Fig. 

 60 a). They are of extraordinary size in some Theropoda (Fig. 70 a), 

 articulating posteriorly with the postorbitals. It has been urged by 

 Jaekel and Gaupp that these bones are not the homologues of the 

 mammalian lacrimal, and should be called by another name, for 

 which postnasal and adlacrimal have been proposed.^ 



Fig. 4. Pantylus, from above. Three fourths natural size. 



Prefrontals (pr). Primitively (Figs. 2, 4, 22) at the upper anterior 

 border of the orbits, articulating with lacrimals, nasals, frontals, and 

 postfrontals, and by a descending process with the palatines. 



Never absent, though much reduced and excluded from the orbital 

 margin in the Theropoda (Fig. 70 a). Sometimes (Fig. 70 c) they 

 articulate with the postorbitals or postfronto-orbitals when the post- 

 frontals are absent as discrete bones. Below, they articulate with the 

 prevomers in the Chelonia (Fig. 30 b), with the palatines and ptery- 

 goids in the Crocodiha (Fig. 69 d). Excluded from the frontals in the 



1 [The cumulative evidence against the views of Gaupp and Jaekel, with regard to 

 the reptilian homologue of the mammalian lacrimal, has been set forth in the Bulletin 

 of the American Museum of Natural History, vol. xlii, pp. 99, 131-135. — Ed.] 



