EYE OF THE ENGLISH SPARROW 



367 



disappears at the outer canthus of the eye. The function of 

 these grooves is evidently to assist in directing the fluid to the 

 openings of the canals and to prevent its escape over the margin 

 of the lids. 



The two lacrimal canals, which lead from the two openings on 

 the under surface at the interior angle of the lids, are easily 

 demonstrated by removing the skin covering them (fig. 9, Ic). 

 They lie just beneath the skin and extend in an anterior direc- 



Fig. 8 Enlarged drawing of the sparrow head with the lids dissected and 

 turned forward to show the openings of the lacrimal canals and the peripalpebral 

 groove, cje conjunctiva of eye, and cj I, of lid; Lg, lacrimal gland; A'^, nictitating 

 membrane; oli and ols, inferior and superior openings of lacrimal canals; p, peri- 

 palpebral groove; Ta, tarsus. 



tion parallel to it. They widen near the openings into a more or 

 less sac-shaped cavity. They are separated from each other 

 for a distance of 2 or 3 mm. by a thin membrane; then they 

 unite into the common duct near the base of the bill. This 

 relatively wide duct now penetrates the bony structures and 

 turns inward and downward to open at the lower portion of the 

 nasal passage in the region of the choana (fig. 10, L). The 

 secretions from the eye are thus directed almost into the mouth 

 cavity, there being a distance of only about 2 mm. from the 



