Susanna Phelps Gage 413 



extensions into the four gill pouches, each of wliich ends in a thin plate. 

 The location of the membranous tips of the gill pouches is indicated upon 

 tiie mesal view (Fig. 4). The gill pouches have also small ventrally 

 projeeting blind pouches ending in a somewliat thickened epithelium, 

 beginnings or protons of the thymus and lateral thyroid bodies. 



The larynx is represented by a slight depression, on the ventro-lateral 

 borders of which is a pair of minute pouches (Fig. 11) similar in appear- 

 ance to the ventral processes from the gill pouches. From their general 

 relations it seems probable that they represent the rudiments of a 5th 

 pair of gill pouches. 



A tubular projection in the roof of the pharynx over the entrance to 

 the esophagus is apparent in several sections. Killian " identified a mesal 

 pouch occupying a position just caudal of the pharyngeal tonsils as the 

 Bursa phanjngea of Meyer. He traced this back to the 11th week of 

 embryonic development. The specimens of the 7th to the 12th week in 

 Cornell University make it apparent that the pouch seen in Figs. 3, 4, 

 at the left of the abbreviation cli. is this same Bursa. 



Trachea. — The trachea (half a mm. long) ends in a pair of widely- 

 spreading bronchi, each with a single slightly enlarged end, the lung-bud 

 (Figs. 3, 11), surrounded by an enlargement in the mesentery. 



Alimentary Canal — The esophagus is small and practically closed 

 through part of its length. It extends to section 107, where it merges 

 gradually into the stomach which shows a spindle-shaped enlargement 

 increasing at its caudal end and turning to the left (Figs. 3, 11)., The 

 lesser peritoneal cavity pushing the stomach to the left (Figs. 2, 17) is 

 shown at its opening into the coelom (Fig. 11, crossed by line pointing 

 to mesentery). 



The stomach narrows again as it merges into the duodenum (Fig. 10). 

 A minute dorsal enlargement of the duodenum is the rudiment of the 

 pancreas (Fig. 3). On the ventral side is found the short bile duct 

 (Figs. 3, 6). As somewhat diagrammatically shown in Figs. 6 and 10, 

 the trabeculge of the liver are in a great sinusoid along the path of the 

 vitelline vein. In Fig. 11 both lobes of the liver are shown from the 

 dorsal side, and in Fig. 6 there is a section through it at the level of the 

 bile duct. The duodenum is enlarged at this point of union with the bile 

 duct, and continues as a tube to its wide (260/a) union with the vitelline 

 sac (Fig. 5). 



The caudal intestine within its free dorsal mesentery (Fig. 5) con- 

 tinues from the vitelline sac in a curve following the back. It enlaro-es 



•Killian. G., Morph. .Jahrbuch, XIV, 1888. 



