60 PATAGONIAN EXPEDITIONS : PAL/EONTOLOGY. 



is continued as a delicate ridge for a short distance in front of the first 

 tooth, and in this region the palatal processes are transversely concave, 

 but for most of their length there is no distinct separation between the 

 palatal and lateral surfaces. The incisive foramina are small and very 

 narrow slits, separated by a slender spine, and the anterior nares are broad 

 and low. 



The mandibular symphysis is short and the edentulous portion of each 

 ramus, which has a narrow and sloping dorsal border, tapers forward very 

 rapidly, becoming slender and compressed and terminating in a rounded 

 point. 



The following measurements of the skull and dentition were obtained by 

 combining two individuals, which were found in the same block of matrix. 

 One of these specimens comprises the anterior part of the rostrum, with 

 the first four teeth and the mandible ; the other is the skull complete to 

 4 on the left side and to - on the right side. The same number, 15,491, 

 has been given to both. 



MEASUREMENTS. 



Upper dentition, length 048 Cranium, width at zygomatic process. . . .038 



" 1-A 021 Forehead, width 045 



Lower dentition, length 052 Occiput, height 037 



" " " T _ T 018 " width at base 044 



Skull, length on median basal line 103 " " over condyles 037 



" extreme length 1 26 Mandible, length of symphysis 015 



Cranium, length to anterior rim of orbit. .059 " depth of ramus below y 012 



Face, length 067 " thickness of ramus below y. . .009 



Rostrum, width at anterior end 018 



Associated with the skulls above mentioned and doubtless belonging to 

 one or other of them, are the fore- and hind-feet, the right ulna entire and 

 most of the left, and parts of both radii. A peculiarity of the fore-arm in 

 this species is the manner in which the ulna and radius are closely applied 

 throughout their length, not forming a radio-cubital arcade; in the left 

 fore-arm the two bones are coossified, which is doubtless an abnormality. 

 The radius is strikingly slender, except at the distal end, which is much 

 expanded, to cover the scaphoid and lunar. 



The manus (Plate XIV, fig. 5) is characterized by the slenderness of 

 the digits, especially of the first, or radial three. The ungual phalanges 

 are narrow, elongate and sharply pointed and form a striking contrast to 

 the massive and powerful claws of P. robustus. 



