THE fiYE. 177 



removed. In ruminants the upper portion is ciliated. The ciUa 

 are especially long in the Giraffe, whose eyelid, margin, and 

 conjunctiva are deeply pigmented, as also the Kangaroo, the 

 frequent involuntary movements of the lids aid in keeping the sur- 

 faces moist. 



The lachrymal gland (Plates 35 and 36, Fig. i, ^), under ordi- 

 nary circumstances, only secretes about sufficient fluid to moisten 

 the surface of the conjunctiva and eyelids, and with the secretion of 

 the Meibomian follicles^ to prevent friction between them in their 

 rapid movements. The surplus being carried off by two small 

 canals ((f), which open at the inner corner or canthiis of the eyelids 

 by two puncta, and unite at the lachrymal sac (f), through 

 which the tears flow into the nasal cavity along the nasal duct. 

 The small fold {plica semilunaris), (h), and vascular protuberance 

 (caruncula), (d), at the inner canthuS, are all that remain in man 

 and apes of the third or nictitating lid, and its lubricating 

 {Harderian) gland. These have been well developed in birds. 

 Fish have no need of, and therefore have no lachrymal gland. 

 Crocodiles have extremely complex appendages to their eyes. 



Tears in all nations are viewed as a sign of grief or pain. 

 Amongst civilised races, the tears which flow from a sudden joy, 

 are probably due to the sudden removal of restraint. Not so in 

 some ancient races of mankind, who have either sunk below or 

 have never raised themselves up to the level of more civilised 

 nations, such as the Andamanese. 



In the interior of the orbit we find that which is, roughly 

 speaking, a quadrilateral, pyramidal cavity, with the apex directed 

 backwards and slightly inwards, and with openings at and near the 

 apex for the optic nerves and vessels passing forwards. Through 

 the optic foramen, at the apex, passes the optic nerve, which takes 

 an additional sheath from every membrane through which it 

 travels. 



From the margin of the bone adjacent arise the four Recti 

 muscles, named respectively Superior, Inferior, External, and 

 Internal (Fig. 2, c.e/.g.). The Levator palpebrce, (a), arises in the 

 same manner, and is inserted into the fibro-cartilage of the upper 

 eyelid, which its action raises. The superior-oblique muscle, {b,) 

 has also its origin here, but passing forwards along the upper 



