No. I.] THE CRANIAL NERVES OF AMPHIBIA. 141 



from the clump of ganglion cells mentioned above. One 

 branch, containing coarse and fine fibres, proceeds cephalad 

 and supplies, in part at least, one of the Mm. levatores arcuum 

 branchialium. 



ThQ fourth br-ancJi (^-{-5) from the main trunk emerges close 

 to the third, immediately cephalad of it. This really consists 

 of two branches, and immediately divides. The dorsal division 

 (5) is the ventral division of the first root, which has been 

 already described, and which separates here (929) to form one 

 of the Rr. laterales. The other division {4) consists of rather 

 large and small fibres intermingled. It immediately separates 

 from the R. lateralis, proceeds directly ventrad a short distance 

 and then bends cephalad. It divides at 938; the outer, smaller 

 division {4. a), containing most of the coarse fibres, soon enters 

 the M. levator Q) lying just outside. The remainder {4 b) pro- 

 ceeds cephalad giving off a minute twig, which appears to enter 

 another M. levator (898). At 888 it divides again, the outer 

 subdivision {4 b^) apparently containing about all the remaining 

 coarse fibres. The inner subdivision {4 b^), the R. laryngeiis, 

 turns mesad (882) and enters the laryngeal muscles (860 ±). 

 The outer subdivision {4 b^ has a complicated and peculiar 

 course. It proceeds directly cephalad, coming to lie immedi- 

 ately above the heart. It now, still proceeding cephalad, slips 

 ventrad close beside the heart, and at 720 appears to give 

 off a fibre or two to a longitudinal muscle near it and near the 

 heart. It divides at 700, and the outer division at 550 ± enters 

 a longitudinal muscle lying above it here. At 627 some fibres 

 which previously separated from the inner division go over to 

 the outer, which divides and innervates the muscle just men- 

 tioned. The remainder of the inner division finally unites with 

 the Hypoglossus, and cannot be followed further as a separate 

 bundle. None but motor branches were observed from the 

 Hypoglossus; and from this fact, as well as from the distribu- 

 tion of the outer division of this branch, that portion uniting 

 with the Hypoglossus may be inferred to have a motor distri- 

 bution. This muscle, or muscles, innervated, certainly corre- 

 spond, in part at least, to Schulze's M. diaphragmato-branchialis 

 medialis. 



