McGregor, Cranial Nerves of CryptobrancJms. 5 1 



name in the frog, since, as indicated above, the ramus mandibii- 

 laris extcrmis and ramus niandibularis internus are separate rami 

 as far back as the facialis ganglion. Ramus hyo-mandibularis 

 pierces the cephalic division of m. depressor maxillae inferioris 

 to which it gives several small twigs, then trends ventrad break- 

 ing up into numerous small branches in m. mylohyoideus pos- 

 terior. The ramus is thus in the main motor but a few sensory 

 branches pass to the skin over m. depressor maxillae inferioris, 

 and probably there are sensory branches to the skin under the 

 jaw. Strong has shown that in the frog these sensory fibres are 

 derived from the ramus communicans IX ad VII. 



Nervus acusticus. The auditory nerve of Cryptobranchus 

 has the usual close relation to the facial. Its distribution is 

 beautifully described and figured by Retzius in Vol. I of Das 

 GcJwrorgau dcr WirbeltJiiere. 



Nervus glossopharyngeus. The most cephalic branch of the 

 glossopharyngeus is ramus coimmmicans IX ad VII. This ramus 

 trends latero-cephalad and unites with the ramus hyo-mandibu- 

 laris at about the point of entrance of the latter into m. de- 

 pressor maxillae inferioris. The next division consists of sev- 

 eral slender branches passing dorsad to the skin on the dorsal 

 surface. Since this division innervates the region of the occip- 

 ital group of lateral-line sense-organs there is a possibility that 

 it represents the ramus sitpratemporalis of Strong. 



The ramus immediately caudad of the preceding is a slen- 

 der branch which passes ventrad to the mucous membrane of the 

 roof of the pharynx. It can be traced cephalad as far as the 

 post-nasal process, lying close to a blood-vessel between the 

 pterygoid bone and the mucous membrane of the roof of the 

 mouth. Herrick finds a somewhat similar ramus in Am- 

 blystoma which anastomoses with the ramus palatinus VII. 

 This ramus seems to be the ramus pharyngeus of Fischer. 



The ramus lingualis lies furthest caudad and is much the 

 largest of the glossopharyngeus branches. After passing latero- 

 caudad over the hyo-suspensorial ligament it gives off a slender 

 cutaneous branch, which anastomoses with a somewhat similar 

 branch of the vagus, supplying the skin cephalad of the branch- 



