12 MEGALONYX. 



The parts within the interior of the nose are too much broken to obtain any 

 very detinite idea of their form. The specimen is also broken in the guttural 

 region so as to expose the capacious sinuses existing between the tables of the 

 cranial bones. 



Sutured Connections of the Bones of the Skull. — As previously stated, in the speci- 

 men under examination the sagittal suture remains open in the form of a deep 

 cleft separating the two sides of the corresponding crest. 



The fronto-parietal sutui"e is completely obliterated, but its position is still trace- 

 able, commencing at the anterior extremity of the sagittal crest, and curving back- 

 ward and downward about the middle of the temporal surface. 



The temporo-parietal suture is serrated, and pursues a nearly straight course from 

 the postero-superior extremity of the root of the zygomatic process downward and 

 forward to the sphenoid bone. 



The occipito-parietal suture remains open in the specimen, and courses along the 

 semicircular margin of the inion until it reaches the temporal bone, when it abruptly 

 turns posteriorly and descends in a line, which is convex inward to the point of 

 separation of the paramastoid and stylo-hyal processes. 



The sutures of the lachrymal and nasal bones are obliterated in the specimen. 



Comj^arison of the Megalonyx Skull of Dr. Dickesons Gollection, with that of Dr. 

 Owen's Gollection. — The skull in the collection of Dr. Dickeson, though less com- 

 plete than that first described, is, nevertheless, also in a comparatively good state 

 of preservation ; and as indicated by the more perfect obliteration of its sutural 

 connections, it belonged to an older individual. (Pis. IV, VI, Fig. 1.) It has lost 

 a portion of the face, the intermaxillaries, the malar bones, and the zygomatic and 

 pterygoid processes, and it is unaccompanied by the lower jaw. The upper jaw on 

 the right side has lost the first molar, and on the left side the last two molars. 



This specimen presents a number of differences from that of Dr. Owen's collec- 

 tion, but none of them, I think, are of sufficient importance to charactei'ize a dis- 

 tinct species. 



The skull is shorter than Dr. Owen's specimen, but in a corresponding degree is 

 both deeper and broader. 



In the lateral view (PL IV), the upper outline is not so nearly horizontal, but 

 above the temporal region is strongl}^ convex, at the forehead is much more de- 

 pressed, and at the face is less convex. 



The inion is more vertical ; and the temporal foss^ possess a greater vertical 

 diameter, though their length is no less. 



The squamous portion of the temporal bone is larger, is more elevated above 

 the general level of the temporal surface, and also is rather more roughened by 

 reticular ridges. The venous foramina in the vicinity of the temporo-parietal 

 suture are larger. 



In the upper view of the skull the anterior portion of the temporal region appears 

 much more prominently convex than in Dr. Owen's specimen. The sagittal crest 

 also is more elevated, and in this instance is not cleft. The ridges diverging from 

 the latter anteriorly, are less prominent, but the post-orbital protuberances are a 

 little more so. 



