MTTSTELUS LJ^.VIS. 151 



perforate the overhanging orbital roof. There they turn back- 

 ward along the dorsal surface of the roof and separate, the 

 special sensory nerve, which is purely a lateral sensory one, 

 innervating the posterior sub-group of the supra-orbital 

 organs, — that is, organs 87 to 93 of that line, while the 

 general sensory branch goes to the general tissues. This pair 

 of nerves together form the first one of the so-called frontal 

 branches of the main nerve, the portiominor of the nerve thus, 

 contrary to Schwalbe's statement (57, p. 184), taking part in 

 the formation of these frontal nerves. Schwalbe says that 

 the portiominor only gives off one branch during its passage 

 through the orbit, that branch being the communicating 

 branch to the trochlearis — a branch that I do not find. 



Slightly anterior to this first pair of frontal branches a 

 second pair is given off, one a general sensory branch, and 

 the other a lateral sensory one destined to innervate supra- 

 orbital organ 86. Both of these branches have a forward 

 instead of a backward course. Anterior to them two or three 

 general sensory branches and five lateral sensory ones are 

 successively given off, the latter branches subdividing and 

 innervating organs 76 to 85 supra-orbital. These five lateral 

 sensory branches all piei'ce the orbital roof by separate 

 foramina, the general sensory branches either accompanying 

 them or traversing separate foramina of their own. All these 

 branches have a forward and upward coui'se. 



Beyond the root of the most anterior one of the five lateral 

 sensory branches above referred to, that is, anterior to the 

 branch that innervates supra-orbital organs 76 and 77, and 

 near the front end of the orbit, the ophthalmicus superficialis 

 itself pierces the orbital roof, and reaches its dorsal surface. 

 In the slightly younger specimens examined by dissection 

 the nerve here traversed a notch in the orbital roof, as shown 

 in fig. 4, instead of piercing it. Shortly before leaving the 

 orbit it passes dorsal to the nervus trochlearis, and there 

 comes into intimate juxtaposition with that nerve, but, as 

 already stated, without any indication whatever, that I could 

 observe, of any interchange of fibres. 



VOL. 45, FART 2. — NKW SERIES. M 



