DEVELOPMENT OP TEETH IN HATTEETA PUNCTATA. 177 



Each palatine lias four teeth, three anterior larger and 

 one posterior smaller. 



In the mandible, number 3 is much larger than the 

 first two; in the middle line over the symphysis is left a gap 

 into which the two first premaxillary teeth are received. Tlie 

 third mandibular " bites '^ posterior to the third premaxillary 

 tooth. In the cheek teeth (10 and 11 respectively on the two 

 sides), the alternation in size is less regular and conspicuous 

 than in the maxilla, and the average size is also less. 



The teeth are not simple cones, but are elongated along the 

 line of the jaw, and overlap one another to some extent. The 

 large maxillary teeth are markedly rounded on their external 

 faces, the internal one being flattened ; the converse is the 

 case with the palatine teeth, the flattened faces being turned 

 towards the maxilla. The mandibular teeth more closely 

 approach the conical form, as do the smaller ones of the upper 

 jaw. 



All the teeth are more or less triangular in side view; the 

 apices of the larger ones in the upper jaw, however, point 

 slightly backwards. 



Embryo S, 2. — 7*5 cm. in length, and was prematurely 

 hatched. The length of skull as measured from sections was 

 11"5 mm., slightly smaller than the last. 



Thei-e are very few teeth of the embryonic series now 

 remaining, and these are evidently being forced to the 

 exterior by the growth of the epidermis. The epidermal 

 cells form a more or less regular capsule, and the tooth 

 usually shows no signs of absorption, being probably shed 

 entire (fig. 12, T. 1). 



In the functional series, we find the first premaxillary 

 tooth smaller than the other two and further removed from 

 the surface. 



The maxillary teeth are about equal in number to those 

 in the skull just described, and show a similar alternation. 

 Posteriorly the dental lamina takes a curious upward then 

 forward course (fig. 10, d. I.), previously losing its direct 

 connection with the epidermis. The eleventh and twelfth 



VOL. 44, PART 2. NEW SERIES. M 



