56 bulletin: museum of comparative zoology. 



where it bifurcates. Each branch gives off a small twig (Plate 2, 

 fig. 4, na. l.^ and na. /.-), which passes out through this gland to the skin. 

 The more lateral of the tAvo bundles again divides, and these three 

 terminal divisions of the ramus (Plate 4, fig. 9) then emerge from the 

 anterior side of the gland to innervate the skin overlying that region. 

 The two small twigs proximal to the three terminal divisions (Fig. 4) 

 supply a somatic sensory innervation to the olfactory epithelium. 



(b) Ramus medialis nasi. After giA'ing off a few fibers to the 

 olfactory epithelium, the median ramus supplies a larger branch 

 {na. m.^) to the skin over the nasal bone; the foramen (for. na. vi.) 

 through which this nerve emerges is clearly indicated in fig. 1, Plate 1. 

 The main ramus then passes cephalad wdthout branching to the 

 extreme tip of the snout to innervate richly the skin anterior to the 

 external nares. Its terminal branches are shown in Plate 2, fig. 4, but 

 not in Plate 3, fig. 6. In its course it keeps close to the internasal 

 septum and the median dorsal part of the premaxillary bone (Plate 4, 

 figs. 8, 9). 



II. Ramus maxillaris (Plates 2> 3, figs. 4, 6, 7, mx.). The second 

 main branch of the trigeminus is given off from the lateral side of the 

 portio major of the Gasserian ganglion. It passes between mm. 

 pterygoideus and capiti-mandibularis to reach the posterior ventral 

 rim of the bony orbit. It makes a circuit of this ventral rim to the 

 anterior side of the orbit where it passes into the marrow cavity of the 

 maxillary bone and continues its course in the upper jaw. Besides 

 numerous rami distributing somatic sensory components, this nerve 

 becomes involved with the superficial sympathetic rami of the head 

 in what may be called the "lachrxTnal plexus," and with the viscero- 

 sensory-sympathetic in the orbital plexus. It will simplify the ac- 

 count to describe first the somatic sensory rami, as far as possible, as 

 though the plexus did not exist and give an account of the latter 

 separately. 



The following branches are given off from the ramus maxillaris: 

 (a) the first branch (mx.^) is given off from the dorsal side. It passes 

 around the anterior side of the m. capitis mandibularis and turning 

 back supplies the skin (Plate 2, fig. 4; Plate 3, fig. 6). In its course 

 it crosses the sympathetic rami in the lachrymal region, but its cutane- 

 ous fibers do not mingle. In some dissections it appears to be inde- 

 pendent, although in figure 7 it joins the lachrymal plexus in such a 

 way that its terminal ramus could not be identified, (b) The second 

 branch (mx.-) also passes across the plexus, where it is difficult to 

 folloAV it in sections, but a dissection, upon being cleared and mounted, 



