CHAP. IX.] 



TEETH : SELACHII. 



261 



Rhinoptera javanica : the row of teeth marked I is one side 

 single, but on the other side is represented by two rows. Fig. 69, 

 lower diagram. OWEN, Odontography, PI. 25, Fig. 2. C. S. M. 

 (Hunterian specimen}. 



399. Cestracion philippi : an upper jaw having the teeth disposed as 

 in the figure (Fig. 70). C. S. M. 



FIG. 70. Upper jaw of Cestracion philippi, No. 399. 



On comparing the teeth of the two sides it will be seen first that 

 the rows do not correspond individually, and secondly that they do not 

 at all readily correspond collectively. Assuming that the rows marked 

 4 on each side are in correspondence (which is not by any means cer- 

 tain) several difficulties remain : for right 5th is larger than left 5th, 

 but left 6th and 7th together are larger than right 6th; right 7th is 

 about the same size as left 8th, but right 8th is larger than left 9th. 

 The proportions in the figure were carefully copied from the specimen. 

 400. " Cestracion sp." [so labelled, but probably not this genus] : 

 lower jaw as in Fig. 71. On the right side the second row of large 

 plates is represented by two rows, properly fitting into each other, 

 but on the left side the plates of the inner side are completely 



