CONTENTS OF A BONE CAVE. 17 



The larger number of specimens received from Dr. van Rijgersma are of a dull 

 rusty-brown hue, and were doubtless derived from one and the same locality, and 

 were found at or near the same time. They include the bones and teeth of the 

 largest specimens of the genus Amllyrluza, while most of the smaller individuals 

 were received at other times, and from differently colored deposits. The mandibles 

 and teeth of two different species are included in this lot, and one of them is pro- 

 bably the A. laiidens, but which one is to be collated with the maxillary bone above 

 described is not certain. As the maxillary teeth of A. latidem differ in the 

 specific character of a greater width from those of A. inundata, it is probable that 

 the inferior molars which bear the same relation to those of A. immdata, are the 

 ones to be described here. Those which present other differences, which are less 

 marked, are referred to another species under the name of Amblyrhiza quadrans. 



Of mandibles referable to the A. latidens, there are both sides of one individual 

 iu a more or less mutilated condition, one only presenting the molar series complete. 

 Seen from the outer side, the summits of all the inferior molars rise an equal dis- 

 tance above the alveolar border, the insignificant excess in height of the first tooth 

 being only individual. But on the inner side the alveolar edge descends forwards 

 so as to leave the first molar projecting to four times the elevation of the fourth. 

 Viewed from above, the molars successively narrow forwards, the first being only 

 half as wide as the fourth. The direction of the transverse enamel bands becomes 

 more oblique forwards externally, so that the anterior column of the first molar 

 stands at an angle of 45 to the long axis of the series. Those of the fourth 

 molar are moderately oblique, and the middle column in the third and fourth 

 molars has the greatest transverse extent. The inner posterior angle marks the 

 middle of the basis of the small coronoid process. The apex of the latter is 

 recurved, and the direction of its plane is 45 from that of the mandible. The 

 inner alveolar border is continued as a ridge for a short distance behind the last 

 molar, and then descends and disappears at the distal foramen. This foramen 

 opens on a horizontal surface or plane which is bounded without by the external 

 border of the ascending limb, and within by the strong ridge which connects that 

 portion with the prominent alveolar sheath of the inferior incisor, The inner face 

 of the jaw is gently concave to the incisor alveolar ridge ; the external face is 

 marked by a fossa, about as wide as the diameter of a molar tooth 25 mm below 

 the alveolar border, and opposite the third and part of the second teeth. 



MEASUREMENTS. 



M. 



Length of series of molars (No. 1) . . . . -058 



" of posterior molar ...... .047 



Projection of posterior above alveolar edge .... .005 



Diameter of fourth molar | fore and aft ' - , 16 



(.transverse .... .016 



of third molar J fore and aft . -013 



(.transverse. .... .015 



e , , (fore and aft . . . .012 



" of second molar 



(transverse ..... .014 



. c (fore and aft ... . .015 



of first molar 4 



(transverse .... -Oil 



Elevation of first molar on inner side ..... -015 



3 April, 1883. 



