416 DR. C. F. SONNTAG ON THE ANATOMY, 



superior oblique. It passes through an arch formed by the 

 capsule of Tenon. The rectus exteriius a.rises by two heads 

 and is inserted as in Man. It is broad and moderately thick. 

 The thir-d nerve crosses both heads instead of passing between 

 them. The fourth nerve passes over both heads as in Man. 

 And the sixth nerve comes out between them before sinking 

 into their ocular surface. The naso-ciliary nerve also crosses 

 both heads. The rectus internus is broad and thick, and its 

 attachments are as in Man. Its nerve, from the superior 

 division of the oculomotor nerve supplies it by several twigs. 

 The inferior oblique arises by fleshy and tendinous fibres from 

 the floor of the orbit a quarter of an inch external to the naso- 

 lachrymal duct. It is not spread out as in Man, but remains as 

 a thin belly, which is inserted farther back into the sclera close 

 to the entrance of the optic nerve on the postero-lateral aspect 

 of the ball (text-fig. 27). The rectus inferior is as in Man. It 

 is, therefore evident that the recti are almost as in Man, but the 

 obliques and levator palpebrse differ. 



The nerves and vessels are described in other sections of this 

 paper. 



The capsule of Tenon is very strong. 



The ophthalmic veins are as in Man. 



On pulling the eye forwards it was seen that the fascia lying 

 next to the eyeball was seen to be well developed, and almost 

 free from fat. The globe itself is relatively smaller than in 

 Man, but the ophthalmoscopic appearances are very similar in 

 both, as pointed out by Lindsay Johnstone (70). 



Auditory App>aratus. 



It is well known that the auricle is less degenerate in the 

 Chimpanzee than in Man and the other Anthropoids. And 

 from the numerous accounts which have been published it 

 appears that the auricle is one of the most variable parts of the 

 external anatomy of the Chimpanzee. Its very complete form 

 in my specimen is shown in Plate I. fig. A. It has few hairs, and 

 Wallis (58) pointed out that it has this featxire in all examples. 

 Darwin (16) noted that neither the Orang nor the Chimpanzee 

 move their auricles, and I was unable to detect any moA^ements 

 on any occasion when I made observations in the Ape House in 

 the Gardens. In Plate II. fig. B it is shown how the auricular 

 cartilage is very complete, and it has a wide, thin peripheral 

 rim. But the human auricular cartilage is a totally different 

 thing. I was unable to detect intrinsic muscles in the cartilage. 



The tympanic membrane cannot be seen through the ordinary 

 aural specula, for it lies at the end of a long, bony external 

 auditory meatus. 



The Eustachian tnbe has no well-marked torus round its 

 pharyngeal end, and I did not detect a salpingo-pliaryngeus 

 muscle. 



