SECOND TRUNCUS BRANCHIALIS VAGI. 103 



more distinct than that of any of the other branchials, and 

 this seems to be the rule among the teleosts. Stannius 

 states that in Ckipea and Alosa this ganglion is fused with 

 the IX ganglion. He does not mention the division of the 

 post-trematic nerve into dorsal and ventral ramuli, 

 Baudelot, however, describes ('83) a somewhat similar 

 condition in the carp, though there it is the pre-trematic 

 ramus which is double, the dorsal ramulus being much 

 larger than the ventral. 



IV. — Second Truncus Branchialis Vagi. 



This division of the vagus gives rise to four branches 

 for the roof of the mouth, two motor and two mixed. 

 First, there are the two purely motor twigs, one, very 

 minute, for the third levator arcus branchii externus (j. I. 

 a. ^.), the other for the single large m. branchialis ob- 

 liquus superior (/«. b. o. s?). The third branch leaves the 

 cephalic face of the post-trematic ramus and passes partly 

 through, partly laterally of the second m. levator arcus 

 branchii internus {2. I. a. i.). In its passage through this 

 muscle it forms an intricate plexus and doubtless inner- 

 vates it, though most of the fibres emerge and anastomose 

 with the more lateral fibres, finally to enter the dentary 

 canal in the upper pharyngeal bones (pharyngo-branchials) . 

 The remaining fibres of this pharyngeal nerve distribute 

 to the mucus membrane of the lateral part of the pharynx 

 (sensory buds and glands) . 



Regarding the levator arcus branchii internus muscles, there seem 

 to be but two muscles in this series. The second one is much larger 

 and longer than the first one. It originates from the skull far ceph- 

 alad at the level of the exit of the third nerve and passes back almost 

 horizontally to its insertion on the second pharyngo-branchial bone, 

 so that it really serves as a protractor of these bones. The first levator 

 arcus branchii internus arises from the skull much farther caudad 



