No. 2304. REPTILIAN CHARACTERS IN MAMMALS— WORTMAN. 



17 



ent backward extension of the maxillary is in reality a distinct element 

 that is separated by suture and represents the quadrato-jugal. The 

 jugal, as well as any representative of the postorbital are apparently 

 missing in the adult. This interpretation of the zygoma of the 

 Lagomorpha gives a clue to the composition of the arch in Ornitho- 

 rJiijnchus, which is without much doubt made up of the usual tliree 

 elements. I can not accept the interpretation figured by Broom/ 

 since there is pretty clear evidence from a fairly young skull in the 

 collection that the lower piece of the arch is separated by suture 

 from the maxillary and is therefore the quadrato-jugal. The bone 

 fio-ured by him as the jugal is much more likely to be the postorbital. 

 In embryo skulls the jugal may be present. 



Carnivora. — In the composition of the jugal arch the Carnivora 

 not infrequently display evidences of the compound nature of the 

 so-called malar. Thus 



■Alas. 



Parci./na.s . 



PslGien. 



Fig. 10.— Ursus horeibilis. Exi. aud. ml., external audi- 

 tory meatus; Mas., jiastoid; Para, mas., paramastoid; Pst. 

 Glen., post-glenoid; Sq., squamosal. 



a large percentage of 

 the skulls of bears show 

 the postorbital process 

 of the zygoma to consist 

 of a distinct element, 

 the suture separating 

 which is very frequently 

 more or less evident. 

 This is likewise often 

 seen in the various spe- 

 cies of the Felidae. In 

 some 8 or 10 fetal skulls 

 of blue foxes the ante- 

 rior part of the zygo- 

 matic process of the^squamosal is cut off as a distinct piece, which I 

 take to represent ! this same element composing the postorbital 

 process of the arch in the Canidae. The same division is sometimes 

 found in the adult skull, and has been figured by me in the extinct 

 Creodont Dromocyon vorax. 



At the junction of the squamosal and the mastoid, near the lower 

 end and just posterior to the external auditory meatus is a distinct 

 bone, which is so constant in the bears as to be almost a distinguishing 

 feature of this group. It sometimes exists as a cap or epiphysis, 

 but in other instances it is united by strongly dentate suture. A 

 similar element is found in the Mustelines, raccoons, and many 

 other species of Carnivora with great frequency. As already noted 

 the same element is seen in certain of the Insectivora and Marsupials. 

 On account of its possible important relationship with the quadrate 

 I propose a name for this bone, already suggested on a former page ( 14) , 

 namely, the Paramo stoid (fig. 10). 



1 On the Stracture and Affinities of the Multitubercuiata. Bull. Amer. Mus., 1914, p. 130. 

 1443S2— 20— Proc.N.M.vol.57 2 



