CONTENTS OF A BONE CAVE. 19 



MEASUREMENTS. 



M. 



Length from apex of symphysis to posterior base of coronoid process .160 



" of symphyscal rostrum ..... .080 



" from base of rostrum to the first molar . . . .012 



" of free inner face of incisor ..... .038 



" " outer " . . .110 



" of alveolus of first molar ..... .018 



" " of second molar . . . . . .011 



" " of fourth molar . . . . .016 



Width " " " . . .016 



" between rami at fourth molars .... .050 



The mandibles, with teeth of the two larger individuals last described above, 

 were sent by Dr. van Ilijgersma in connection with numerous bones of the skeleton, 

 which, in color, mineral character, and dimensions, are so appropriate to them, that 

 I do not hesitate to believe that they belong to the same individuals, excepting in 

 so far as they include portions of the skeleton of the A. quadrans. Of these the 

 vertebra; first claim attention. 



The atlas is depressed in form, and the condylar fossa? are divergent upwards. 

 The odontoid fossa viewed from the front has only half the diameter of the neural 

 arch. The transverse processes expand backwards and outwards, their postero-ex- 

 ternal angle being behind the plane of the facets for the axis, and the border being 

 a regular curve from a short base behind the margin of the condyloid fossa. The 

 axial facets are wide oblique ovals separated below and bounded by a deep groove 

 at the base of the neural arch. The neural spine is lost. 



The neural canal of the axis is subquadrate, and a little wider than deep. The 

 neural spine is strongly keeled in front, the inferior extremity of the keel project- 

 ing beyond the arch. The posterior face of the spine is subconcave. The poste- 

 rior zygopophyses are well developed. The posterior articular face of the cerebrum 

 is a hexagon, a little wider than deep, and its vertical plane is directed a little for- 

 wards above. The condyles for the atlas descend to the plane of the inferior sur- 

 face. 



DIMENSIONS OF CERVICAL VERTEBRAE. 



M. 



Length of atlas below < "east (median) . .019 



(greatest . . . . .025 



Width of atlas 5 antcl ' iOT| y -059 



c posteriorly . . . . . .108 



Length of transverse process behind ..... .032 



Depth of " " at base . . . . .020 



Width of neural canal .... . . .025 



Vertical diameter of facet for axis . . . . .016 



Length of centrum of axis (without odontoid) . . .024 



of odontoid process .... .014 



Diameter of posterior face of centrum \ ver 



(transverse . . .023 



Greatest width of centrum . . ... .040 



Interior elevation of neural arch ... . .018 



Diameter of neural spine { tral > s rse - 020 



( antero-postenor . . . .018 



