332 H. W. NOERIS AND SALLY P. HUGHES 



the levator palatoquadrati muscle and enters a foramen in the 

 lateral wall of the cranium, passing into the cranial cavity. At 

 the level of the posterior wall of the nasal capsule it enters a 

 foramen of exit in the dorsolateral wall of the cranium, emerging 

 just ventral to the supraorbital lateral-line canal, lateral to the 

 ramus oph. spf. VII. As it runs anteriorly in this position it 

 divides first into two main branches, then into smaller ones 

 farther on. As described by Allis, most of its terminal branches 

 curve ventrally and then posteriorly around the anterior wall 

 of the nasal capsule, supplying the skin on the ventral side of 

 the snout. The distribution of the profundus in Mustelus is 

 thus in sharp contrast to that in Squalus, since in the latter the 

 final terminations are dorsal and lateral, reaching anteriorly to 

 the tip of the snout. 



4. The ramus ophthalmicus superficialis V 



Under this designation are included certain small nerves of 

 somatic sensory composition that have a common central origin 

 and a special peripheral distribution, i.e., to the skin dorsal to 

 the orbit. Under this heading we may recognize in Squalus 

 three groups of fibers: 1) in a cross-section of the head immedi- 

 ately anterior to the thin anterior part of the profundus ganglion 

 there is seen a small but distinct band of fibers on the ventral 

 border of the ramus ophthalmicus superficialis VII, in size less 

 than one-fifth of the profundus nerve (fig. 10, os. V 1); 2) in the 

 same section there may be seen on the mesial dorsal border of 

 the same nerve trunk a smaller band (os. V 2); 3) dorsolateral 

 to the r. oph. spf. VII may be seen one or more small nerves 

 (os. V 3). Proximally the fibers of 1) may be followed in the 

 angle between the ramus oph. spf. VII (ganglion) and the pro- 

 fundus ganglion (figs. 11, 22, 32, and 35). As the profundus 

 root fibers emerge from their ganglion, the two nerves run side 

 by side, the superficial ophthalmic fibers dorsal in position, but 

 so completely merged are the two nerves that it is difficult in 

 many instances to distinguish between them. But as pre- 

 viously stated, the fibers of the r. oph. spf. V, which at first lie 



