EXTERNAL STRUCTURE. gg- 



q Spinal marrow, extending throug-h a canal in the centre of the bonea of the neck 

 back, and loins, to the extremities of the tail, and from which the nerves of feeling 

 and of motion, that supply every part of the frame, except the head, arise. 



r Septum narium, or cartilaginous division between the nostrils. 



s The same cut oft' at the lower part, to show the spongy, turbinated, turban-shaped. 

 bones filling the cavity of the nostril. 



* Palate. 



u Molar teeth, or grinders. 



V Inferior maxillary bone, containing the incisor teeth or nippers. The canine tooth, 

 or tush, is concealed by the tongue. 



w Posterior maxillary, or lower jaw with its incisors. 



X Lips. 



y Tongue. 



z A portion of the os hyoides, or bone of the tongue, like a Greek u, v. 



1 Thyroid, helmet-shaped, cartilage, inclosing and shielding tlie neighouring parts. 



2 Epiglottis, or covering of the glottis, or aperture of the wind-pipe. 



3 Arytenoid, funnel-shaped, cartilages, having between them the aperture leading int« 



the trachea or wind-pipe. 



4 One of tlie chordce vocales, cords or ligaments concerned in the formation of the voice 



5 Sacculus laryngis, sac or ventricle of the larynx, throat, to modulate the voice. 



6 Trachea or wind-pipe, with its different rings. 



7 Soft palate at the back of the mouth, so constructed as almost to prevent the possi 



bility of vomiting. 



8 Opening from the back part of the mouth into the nostril. 



9 Cartilage covering tlie entrance into the Eustachian tube, or communication between 



the mouth and internal part of the ear. 



10 (Esophagus, or gullet. 



11 Cricoid, ring-like, cartilage, below and behind the thyroid. 



12 Muscle of the neck, covered by the membrane of the back part of the mouth. 



REMARKS ON THE BONES OF THE HEAD, ETC. 



In the sheep and occasionally in the ox, rarely in the horse, the larvae of 

 maggots produced by certain species of flies, crawl up the nose, lodge 

 themselves in these sinuses, and produce intolerable pain. 



Veterinary surgeons have availed themselves of these sinuses, to detect 

 the existence of glanders, that disease so infectious and so fatal. They 

 may suspect that a horse respecting which they are consulted is glandered. 

 It is of great consequence to be sure about it. The safety of the whole 

 team may depend upon this. It may be a puzzling case. There may be 

 no ulceration of the nose within sight. The glands under the jaw may 

 not be close to, and seemingly sticking to the bone, which is a common 

 symptom, yet for a considerable time there may have been a discharge 

 from the nostril, and the horse is out of condition. On the other hand, 

 some slight ulceration may be detected in the nostril, but the horse eats 

 well, works well, and is in good plight. From the closest examination 

 of the animal, no horseman, and no veterinary surgeon can give a decided 

 opinion. 



If, however, the horse be glandered, there will probably be considerable 

 ulceration in the upper part of the cavity of the nose, and a collection of 

 matter there. To detect this, the veterinary surgeon sometimes makes an 

 opening into these sinuses. He may do this with perfect safety. On that 

 part of the frontal bone, which lies between the eye and the pit above it, and 

 above the inner corner of the eye, there is, on either side, a small depression 

 or hole (see fig. b b, cut, p. 66), which may be easily felt in the living 



