140 



HEFFERAN, 



[VOL. II. 



the combinations of definite and indefinite teeth, the left jaw 

 having 8 to 4, the right 6 to 6. Figs. 5 and 6 are from small, 

 young animals, and the jaws are seen to be more slender with 

 numerous fine teeth, 13 on the right and 12 on the left jaw. 



The specimen drawn in Fig. 7 was interesting in regard to 

 the indefinite teeth. The left jaw presented the usual appear- 



FlG. I. 



FIG. 2. 



FIG. 3. 



FIG. 4. 



FIG. 5. 



FIG. 6. 



FIG. 7. FIG. 8. FIG. g. 



FIGS. i-8. Variation and abnormalities in teeth on opposite jaws. 

 FIG. 9. Abnormal segment. 



ance of six indefinite teeth placed fairly regularly and six 

 definite teeth. On the right jaw the point was worn smooth, 

 leaving only four definite teeth, while below three normal 

 indefinite teeth was a series of five small ones placed very 

 close together instead of three as on the opposite jaw. This 

 may indicate a tendency towards regulation by the production 



