A NEW FOSSIL PORPOISE FROM MARYLAND. 



173 



internal accessory cusp, on a lower level than the main cusp, and also a smaller 

 an tero-i n tern al accessory cusp situated a little lower. As in the maxillary teeth 

 there is below the postero-internal cusp a smaller protuberance which may, 

 perhaps, be regarded as a part of the cingulum, and a similar one below the 

 antero-internal cusp. The posterior cusp may be distinguished at least as far 

 forward as the 7th tooth from the posterior end of the series, and the prominence 

 of the cingulum still farther forward. On the posterior teeth of the series, th< 

 posterior longitudinal ridge traverses the postero-internal accessory cusp. 

 The height of the crown increases a little toward the anterior end of the series, 

 and among the teeth preserved is one which has a longer crown than the average 

 of the others, and is less curved and nearly terete and smooth. This is probably 

 one of the terminal mandibular teeth. 



The cingulum is more strongly developed than in the maxillary teeth, appear- 

 ing not only at the base of the longitudinal ridges, but also around the bates of 

 the accessory cusps. In the middle of the series, it is distinguishable nearly, or 

 quite, around the teeth. 



The roots of the teeth which are regarded as belonging to the mandibular 

 series are less curved than those of the maxillary ones, or nearly straight, but 

 not otherwise different. In both series the roots are of a chocolate-brown color, 

 while the crowns are of a much paler, yellowish brown. The teeth are hollow 

 and the tapering extremity of the root open below. 



The dimensions of the teeth are given in the following table. The numbers 

 used to designate the teeth which are in the natural position show their actual 

 place in the row, counting from the posterior end. The numbers for the detached 

 teeth are arbitrary, but the latter are arranged as nearly as possible in what is 

 believed to be the natural sequence, no allowance being made for missing teeth, 



for those 



The total length is given for each tooth as now preserved 



but as many have the root defective this measurement in the majority of cases 

 will be of little use, except in identifying particular teeth in any discussion of 



Measurements of the Teeth. 



Upper. 



Measurements. 



Left, tn situ. 



Total length 



Length of crown 



Greatest diameter of crown 



at base 



Greatest diameter of root . 

 Least diameter of extrem- 



ity of root 



Root a little defective. 

 Root defective. 

 1 Nearly all of root lacking 



Left, detached 



1 



2 



l . 



2 



mm. 



26.8 



9.6 



1 3 



1 4 



5 



mm. 

 27.2 1 

 11.4 



mm. 

 7.6 



mm. 

 8.2 



mm. 



29.4 



9.8 



mm. 



26.6 



9.9 



mm. 

 27.2 1 

 10.8 



5.0 

 4.6 



5.0 

 5.2 



5.6 

 5.5 



5.0 

 5.6 



5.2 

 5.6 



5.1 

 5.5 



5.4 

 5.7 



! 





1.5 



1.8 



1.4 1 



2.0 l! 



! 2.0 1 



6 



7 



mm. 

 25.5 1 

 10.6 



mm. 



21.0 1 

 10.4 



5.6 



5.6 



2.4 1 



5.3 

 5.4 



8 



mm. 

 14.0* 



10.2 



5.2 



I 



mm 

 19.8 1 



4.3 



4.6 



2.1' 



10 



mm. 

 11.9' 



8.9 10.8 



