16 
Proceedings of the Royal Society 
The author then discussed the homologies of the incisor teeth 
with reference to the intermaxillary bones, and the nature of the 
precanine tooth. He believed that the precanine should be regarded 
as In 3 , and that the missing incisor in the normal human dental 
arcade is In 2 . Whilst agreeing with Th. Kolliker in his criticism 
that the teeth and jaws arise quite independently of each other, and 
only become related secondarily, yet from the fact that in so large a 
proportion of the casts a tooth, which from its position must be 
referred to the incisor series, was situated between the canine and 
the cleft could scarcely be without some significance, and from the 
frequency of its occurrence, should not be regarded as a mere acci- 
dental displacement of a tooth germ. The very frequent presence 
of a precanine tooth may therefore be regarded as supporting 
Albrecht’s view of the position of the cleft. 
Albrecht has, however, had the advantage of examining several 
skulls in which the alveolar cleft was seen to separate the inter- 
maxilla into an inner and an outer part, each carrying its appropriate 
incisor or incisors. In addition to the skulls of the horse and the 
calves referred to in his first essay on this subject, he has since de- 
scribed and figured an adult human skull in the University of Kiel, 
in which a right cleft existed in the corresponding intermaxilla, 
and the right maxillo-intermaxillary suture coexisted with and was 
quite distinct from it ; a new-born infant with double cleft, in which 
the same suture was present ; the jaw of a child about one year old, 
in the museum at Ghent, in which, with a left cleft in the corre- 
sponding intermaxilla, a left maxillo-premaxillary suture was present. 
In all these cases the part of the intermaxilla which was situated 
outside the cleft contained the socket for the precanine incisor. 
The anatomical evidence will therefore justify the statement that, 
in a proportion of cases of alveolar cleft palate, the cleft lies within 
the intermaxilla, the cleft coexisting with the maxillo-intermaxillary 
suture, and an incisor tooth is situated in the interval between the 
cleft and the canine of the same side. 
In the group of cases of alveolar cleft in which no precanine 
tooth intervened between the canine and the cleft, it is not impro^ 
bable that one may find examples of a cleft occurring in the plane 
of the maxillo-intermaxillary suture* and not within the intermaxilla 
itself. Wherever a suture exists, there, of course, a possibility of 
