61 On the Dentition of Pella Burnupi. 
the inner side cutting-point increasing slowly in size, and the 
former being slightly directed towards the central tooth. 
A number of intermediate teeth show a gradual reduction 
of the reflected portion from tricuspid to bicuspid, the median 
cutting-point and, more especially, the inner cutting-point 
increasing in length. 
Marginals quadrangular, much broader than long, triden- 
tate, the median denticle being the strongest. , The eighteenth 
tooth sometimes with four denticles; the last with one only 
rudimentary. ; 
Animal.—Tail rounded, slightly tapering, with a mucous 
tail-gland. ‘There is a pedal line and diagonal grooves on 
the sides of the foot. 
Note.—I also examined the dentition of Vitrina Hudsonie 
Benson, from South Africa, which proved to be a Helicarion, 
as I anticipated. 
