18 WILLIAM A. LOCY AND OLOF LARSELL 



Since the orifices of the recurrent bronchi are usually close to 

 the direct opening into the air-sacs, attention should first be 

 called to Campana's (75) analysis of orifices of the air-sacs: He 

 divides them into two groups, the monobronchial and the poly- 

 bronchial, according to the number of openings which they ex- 

 hibit. The polybronchial orifices are further separated into two 

 categories, the simple and the mixed polybronchials, the simple 

 polybronchial being composed of several openings of one grade 

 (parabronchi) , and the mixed polybronchial embracing openings 

 of two grades, or, as in the case of the interclavicular and the 

 anterior intermediate, uniting two neighboring sacs. Juillet ac- 

 cepts Campana's terminology but substitutes a clear basis of 

 distinction for his confused account of polybronchials. This dis- 

 tinction consists in recognizing direct and recurrent orifices as the 

 components of the polybronchials. A monobronchial orifice must 

 necessarily be direct, but a polybronchial group may be com- 

 posed of both direct and recurrent orifices (mixed polybronchial 

 or of recurrent orifices only (simple polybronchial). 



According to this analysis, which is in harmony with the de- 

 velopmental history, the cervical sac has a direct monobronchial 

 orifice only, since it does not possess recurrent bronchi. A num- 

 ber of branches of the first entobronchus ramify posteriorly into 

 the lung from a point nearly opposite the direct orifice of the 

 cervical sac. These possibly serve the same purpose as the re- 

 current bronchi of the other air sacs, but do not appear to be 

 developed from the sac itself as are the tubes which have been 

 called recurrent bronchi. 



The interclavicular air-sac is connected with the lung by two 

 groups of orifices. The more mesial orifice, which is of the mono- 

 bronchial direct type, opens into a short tube, the interclavicular 

 canal, which also receives the direct orifice of the anterior inter- 

 mediate sac. This short tube in turn communicates with the 

 third entobronchus. 



The more lateral group of interclavicular orifices is mixed poly- 

 bronchial, having both a direct and several recurrent orifices. 

 The direct orifice is the opening of the ventral tip of the lateral 

 branch of the first entobronchus, from which as already described 



