144 ANATOMY OF VERTEBRATES. 



lated exterior, and emits its viscid secretion by a short duct which 

 opens beneath the third lid. The ' lacrymal gland/ fig. 59, d, 

 lies at the posterior and external part of the eyeball ; in the 

 Goose it is of a flattened form, about the size of a pea, and pours 

 its thinner transparent secretion, by a short Avide duct, upon the 

 inside of the outer canthus of the eyelids. The naso-lacrymal 

 conduit commences by two apertures at the nasal canthus, and 

 terminates below and a little before the middle turbinal. In the 

 Ostrich there is a glandular prominence at each 'punctum,' ana- 

 logous to a ' caruncula lacrymalis,' but this structure is not 

 present as a rule in Birds. 



Besides the two glands which serve to lubricate and facilitate 

 the movements of the eyeball and eyelids, there exists another 

 gland which from its position in or near the orbit seems to belong 

 to the lacrymal group ; but its secretion is exclusively employed 

 upon the pituitary membrane of the nose, and it corresponds 

 rather to the nasal gland of Serpents. In many water and marsh 

 Birds the gland in question is lodged in the superorbital fossa, 

 before described, p. 61 ; but in most Birds it is situated within 

 the orbit, either beneath the nasal or between it and the maxil- 

 lary : in the Woodpecker it is found in the subocular air-cell. I 

 have detected it in one or more species of every order of Birds. 

 In the Anserines the gland is large, and seems to complete the 

 upper margin of the orbit, fig. 5Q, k, and is enclosed in a dense 

 fibrous capsule. It is composed of ramified follicles, with cellular 

 walls. In the Albatross and Penguin it sends two or three ducts 

 to the nasal cavity. 



