H6 



[January, 



maxillary bones sufficientiy to £:ive them a determinate form, and their appear- 

 ance, when magnified, is represented in the figures 1 and 2, which were taken 

 from the specimens through the aid of the camera lucida. 



Fi-. 1. 



Fig. 2. 



b-- 



Fig. ] represents the superior maxillary and intermaxiMary bones, much mag- 

 nified, of a human embryo. The diawing was taken from the right side through 

 the aid of the camera lucida, which reverses its position, a. superior maxillary 

 bone; b. intermaxillary bone; c. line of articulation between the two bones; 

 d. falatine process; e. alveolar groove. 



Fig. 2 represents the antero-inferior surface of the sepnrated intermaxillary 

 bone, much magnified. (From the left side, but reversed by the cameio.) a. ascend- 

 ing or nasal process; 5. articulating surface for the superior maxillary bone ; 

 c, incisor alveoli. 



The greatest breadth of the two bones in apposition is one line and two-thirds; 

 the greatest height, being at the ascending or nasal process, is one line. The 

 two pieces present a facial portion, consisting of the ascending or nasal process 

 and part of the body of the bones ; an alveolar ridge and groove and a palatine 

 process projecting backward from the superior maxillary bone. They are easily 

 separable at this period, and the articulation passes through the alveolar ridge, at 

 a point corresponding to the separation between the incisor alveoli and the canine 

 alveolus, and extends transversely inwards behind the incisor alveoli, and verti- 

 cally upwards, dividing the nasal process into two nearly equal portions. On 

 the posterior surface of the nasal process the articulation is at the bottom of a 

 comparatively deep and wide groove, which, however, does not appear to be part 

 of the lachrymal canal, as the latter appears afterwards and external to the former 

 groove. The preparations exhibiting these interesting points which prove the 

 existence of the same law, throughout the animal kingdom, governing the forma- 

 tion of the upper maxillary bones, I present for the inspection of the members of 

 the Academy. 



In an embryonic skeleton in the Wislar Museum, measuring three and one 



