2 ON THE ORIGIN AND DEVELOPMENT OF THE 



of the palate and dental arches. The cheeks were divided 

 transversely from the commissures of the lips with fine scis- 

 sors ; the jaws were separated, removed, and fixed to the 

 bottom of a small capsule full of water. The point of the 

 tongue was removed. The configuration of the mouth was 

 then determined by means of a half-inch lens and two needles, 

 bent at the points, and fixed in slender handles. 



Upper Jaw. The roof of the mouth was bounded an- 

 teriorly and laterally by the free edge of the lip (a, Fig. 2), 

 which is at this age thin and of great transverse extent. 

 Within the lip (a\ but separated from it by a groove (6), 

 to be more particularly described afterwards, there was 

 observed a lobe of a horse-shoe shape (c), narrow anteriorly at 

 the median line, broader, flatter, and of a rounded form on 

 each side posteriorly. Coming out from above the internal 



posterior edges of this lobe (c), and 

 firmly adhering to it, two other 

 lobes (d d) were seen ; flat, rounded, 

 and curving backwards and in- 

 wards posteriorly, gradually dis- 

 appearing by pointed extremities 



anteriorly. From the posterior extremities of each of the 

 lobes now described (d d), and of the horse-shoe lobe (c), 

 a thin semitransparent membranous fold (e e) passed back- 

 ward on each side, attached externally to the sides of the 

 capacious bucco-pharyngeal cavity, bounded internally by a 

 free edge opposed to its fellow of the opposite side, and 

 terminating posteriorly on the lateral walls of the pharynx. 

 Adhering to the inferior surface of each of these folds was 

 seen a smaller lobe (//) somewhat similar to the two last, 

 and situated a little behind them. The needle placed under 

 the folds showed that they were free and floating, except at 

 their exterior or adherent edges, and that they constituted a 

 partial division of the large common nasal, buccal, and pharyn- 



