CONTENTS OF A BONE CAVE. 15 



MEASUREMENTS OP TEETH. 



M. 



Long, diameter of fourth molar ..... .017 



Transverse " ..... .014 



Long, diameter of third alveolus . . . . .016 



Transverse " . . . . . .014 



Long, diameter of second alveolus ..... .013 



Transverse " " ..... .014 



The form of the crown of the last molar differs from the corresponding tooth 

 of the A. latidens in its greater anteroposterior than transverse diameter; measure- 

 ments which are equal in the latter species. This is due to the greater anterior 

 projection of the middle dentinal column on the outer side, and the consequent 

 obliquity and transverse shortening of the anterior column in A. quadrans. The 

 section of the tooth in this species is 8-shaped; in A. latidens nearly quadrant- 

 shaped. The lateral groove in A. quadrans is on the inner side at the front of 

 the middle column; on the outer side, behind it. 



The coronoid process begins opposite the third column of the last molar, and 

 its base terminates opposite to the dental foramen. The incisive alveolus reaches 

 to this foramen, which is at the base of the flat front of the ascending condylar 

 portion of the ramus. The external fossa of the ramus is an inch below the 

 alveolar border, and is opposite the septum between the second and third alveoli. 

 There is a distinct masseteric fossa, as indicated by a portion of its anterior part. 

 The anterior border extends to a point one-half inch behind that below the pos- 

 terior edge of the fourth molar. 



MEASUREMENTS. 



M. 



Length of inferior molar series (anterior part of m. 1 estimated) . .060 

 " from m. 4 to mental foramen ..... .025 



" of coronoid process from base ..... .014 



" of base of coronoid process . . .030 



Width of base of condyloid branch at foramen . . . .020 



Diameter of dental foramen ...... .020 



" of external fossa ...... .013 



I mention here a superior incisor tooth, which is in dimensions intermediate 

 between the largest and smallest of the genus. I do not know whether it repre- 

 sents a distinct species from those possessing the usual form of incisor, or whether 

 its peculiar character is abnormal. With the surface of other incisors it is openly 

 grooved along the middle in a perfectly regular manner. The surface on the inner 

 side of the groove is plain ; on the outer side, the front is convex. Width of front 

 m. 014; depth of shaft .015. 



AMBLYRHIZA LATIDENS, Cope. 



Loxomylus latidens, Proceed. Amer. Pliilos. Soc. 1870, p. 608. 



A number of bones and teeth from Simson's Bay came associated in one pack- 

 age, and agree in having a paler color than the specimens contained in other pack- 

 ages. Among them is a portion o,f the right maxillary bone of an AmbfyrJtlza, 



