No. 2304. REPTILIAN CHARACTERS IN MAMMALS— WORTMAN. 



21 



this evidence is fully known in the case of Khynchocyon, it will be in 

 no wise different. 



It is stated in Cunningham's Human Anatomy ^ in speaking of the 

 ossification of the malar, "the malar ossifies in membrane most 

 probably from three centers, disposed as follows : One in the posterior 

 part of the bone, the other two in connection with the orbital process 

 and orbital margin. Appearing as early as the eighth week, these 

 centers are confluent by the beginning of the fifth month of fetal 

 life." Again, it is stated 

 in Gray's Anatomj^, 

 Spitzka, 1913, in speak- 

 ing of the same subject: 

 "The malar bone gener- 

 ally ossified from three 

 centers, which appear 

 about the eighth week- 

 one for the zygomatic 

 and two for the orbital 

 portion — and which fuse 

 about the fifth month of 

 fetal life. The bone is 

 sometimes, after bu'th, 

 seen to be divided by a 

 horizontal suture into an 

 upper and larger and 

 a lower and smaller 

 division." 



Taking first the bone 

 developed in connection 

 with the postorbital proc- 

 ess of the parietal, in 

 Khynchocyon, at the up- 

 per and back part of the 

 rim of the orbit, it is to 

 be observed that it not 

 onh' occupies the same 

 position, but is very much 



PslO. 



Pmx. 



pt. 



Fig. 12.— Procolophon trigoniceps. After .Smith Wood- 

 ward. Ft., frontal; Ju., jugal; La., lachrymal; Lai. 

 Temp, y., lateral TEMPORAL vacxhty; 1/r., maxillary; Na., 

 nasal; 0., orbit; Pa., parietal; Pmx., premaxillary; Pr. 

 P., prefrontal; Pst. P., postfrontal; Psi. 0., postoreital; 

 Pt., pterygoid; Quad., quadrate; Q«. J., quadratojugal; 

 iSj., squamosal; Sup. T., supratemporal. 



alike in form to the corresponding bone in certain reptilian skulls. 

 This element is therefore to be homologized with the postfrontal of 

 the reptile. This is its exact position in such a reptilian type as Pro- 

 colophon trigoniceps, of the South African Karoo bed (fig. 12), as figured 

 by Smith Woodward. ^ It is important to note, moreover, that it has 

 the same general shape in the two, being a long slender bone, occupy- 



> Article, Osteology, by Arthur Thompson, 1902, p. 133. 

 ' Vertebrate Paleontology, 1898, p. 149. 



