244 



THE MERYCOIDODONTID^ 



advance of the glenoid surface, the malar is very deep beneath the orbit and extends back to the 

 glenoid surface, and the squamosal part is short and weak, with a slight rise reaching its maximum 

 elevation above the glenoid surface. The facial vacuities are large, extending posteriorly to a line 

 through the middle of the orbits. The nasals are narrowest about opposite the anterior orbital 

 margins and widen gradually toward the front, without the abrupt flare at the maxillary suture 

 seen in C. lullianus, for example. Posteriorly they terminate roughly in a point, with merely a 

 thread of the frontal wedging between for a short distance. The nasals are more reduced than in 

 C. lullianus, for example, and end nearly on a line across the anterior orbital margin. In the latter 

 species the posterior nasal bones form a double point, with a sizeable wedge of frontal between. The 

 lacrimal bone is small on the face and has a small fossa. The frontals are typical, with a sagittal 

 ridge medially, flanked by a concavity which is bordered by the elevated supraorbital margins. 

 The orbits are rather small and, as usual, highly elevated, with a nearly circular outline. The 

 temporal ridges unite farther back than normal, being about on a line with the anterior part of the 

 glenoid articular surface. The sagittal crest is short, sharp, and high. The supraoccipital crest is 

 mainly transverse and overhangs about to the posterior edge of the occipital condyles. The brain 

 case is moderately full and laterally expanded. The external auditory meatus is large and high 

 and faces mainly backward, but slightly outward and upward as well. The palatonarial border is 

 U-shaped, rather than V-shaped as is more normal, and extends forward to a line across the posterior 



-pnt I 



-pmv 



Fig. 170. — Cyclopidius densus (Loomis). 

 Superior dentition. HT. Cat. No. 22-595 

 A.M. Deciduous premolars above. Nat. size. 

 (After Loomis, 1925.) 



Fig. 171. — -Cyclopidius densus (Loomis). 

 Inferior dentition. HT. Cat. No. 22-595 

 A.M. Deciduous premolars above. Nat. size. 

 (After Loomis, 1925.) 



of M 3 . The palate is wide and shallowly vaulted. The basicranial axis is shallow, and the glenoid 

 articular surface is moderately convex downward. The postglenoid process is composed of the usual 

 two bones, with the squamosal part very thin. The bullas are large and the paroccipital process is 

 wide transversely at the base and tapers rapidly inferiorly to a point about 34 mm. below the 

 glenoid surface. Index: 0.72. 



Mandible: The symphysiodental angle is about 45°. The coronoid process is somewhat longer 

 than normal, with a narrow sigmoid notch, and the gently convex condyle is situated almost over the 

 middle of the ascending ramus. The masseteric fossa is moderately shallow and elongate but rather 

 extensive. 



Foramina: The infraorbital is above P 3 ; the supraorbital (frontal) is near the temporal ridge, 

 about halfway between the sagittal suture and the upper orbital margin. 



Dentition: The teeth are, as usual, strongly hypsodont. This species has three known inferior 

 incisors. Loomis states that P 4 has no pit in the anteroexternal corner, while P 3 is markedly short- 

 ened from front to rear by the reduction of the anterior portion. This is also true of P 1 and P . 

 P 4 is characterized by the extreme thickening of the posterior crest. P 3 shows the same character- 

 istic, but to a lesser degree. 



Loomis (1925A, pp. 246-247) writes as follows regarding the dentition: 



The milk teeth show the same characters as the permanent, and are typical of the phylum. The fourth 

 upper deciduous premolar is molariform, while the tooth in front of it corresponds roughly to the third permanent 

 premolar. In the lower milk series, the fourth premolar resembles molar 3 of the permanent dentition, though 



