Eyelids and Lachrymal Apparatus of Birds. 
15 
presents a clam-like arrangement behind which the corneal debris, 
tears and viscid fluid from Harder’s gland have meantime lodged. 
This mixture is now carried or pulled upon the outer margin and 
external surface of the third lid (instead of being pushed) toward 
the entrance of the lachrymal canals. The tip or point of the fluke 
of the marginal anchor and, consequently, the marginate band of 
the nictitating membrane is, where it touches them at all, in close 
opposition to the conjunctival lining of the true lids. 
It will readily be seen that this disposition of the parts greatly 
facilitates the rapid transportation of lachrymal debris in the direc- 
tion of the drainage outlet, the true lid preventing fluids from find- 
ing their way over the marginal band and onto the cornea. 
This barb-like, or plicated arrangement, at the free border of 
the nictitating membrane has never been lacking in any of the 
Fig. 9 — English Sparrow with the Lids Dissected off and Turned For- 
ward to Show the Openings of the Lachrymal Canals, ol. on their inner 
surface; cj, conjunctiva; Lg, lachrymal gland; N, nictitating membrane; T, 
tendon from the pyramidalis muscle to the nictitating membrane; Ta, out- 
line of tarsus, x 4. (Wood and Slonaker.) 
hundreds of sections examined; it is difficult to understand, there- 
fore, why they are omitted from the drawings and photographs of 
Fumagalli and others who picture the minute structures of this 
organ. 
Furthermore, neither Slonaker nor the writer has been able to 
find in Passer the smooth muscle fibres in the free border of the 
nictitating membrane described by Doenecke ( Inaug . Diss., Leipzig, 
1899 and Internat. Monatschr, f. Anat. u. Physiologie, 1899, p. 
129). 
Another important organ of the lachrymal apparatus of Birds 
lies at the superior-internal angle of the eye. This is the gland of 
Harder, or the deep gland of the third eyelid, whose excretory canal 
opens below the nictitating membrane. Its color is yellowush, and 
