CONTRIBUTIONS TO ZOOLOGICAL PATHOLOGY. 
347 
well — to walk five miles an hour ; the ratio between the two ap- 
pearing to be about as 5 to 4. But how would these relative 
differences stand, came they to be multiplied] Would a horse walk 
a hundred and twenty-five miles while a man was walking a 
hundred I 
CONTRIBUTIONS TO ZOOLOGICAL PATHOLOGY. 
By JAMES Mercer, M.D. , Fellow of the Royal College of Sur- 
geons, and Lecturer on Anatomy, 8$c. Edinburgh. 
[Continued from p. 269.] 
YI . — On the normal Structure and abnormal Conditions of the 
Larynx in the Horse. 
Muscles of the Larynx. 
The muscles of the larynx may be arranged into two groups, 
an extrinsic and an intrinsic : the former embracing the special 
depressors of the os hyoides, and the latter, all those that perform 
the numerous and complicated movements of its osseous mechanism. 
As the former group act only on the larynx, as a whole, and not on 
its individual portions, their consideration may be here dispensed 
with. The intrinsic group includes nine pairs and a single muscle, 
which may be arranged as follows : — 
External C Crico-thyroidei 
muscles { Thyro-hyoidei 
' Crico-arytenoidei superiores, vel postici 
Crico-arytenoidei inferiores, vel laterales 
Thyro-arytenoidei anteriores, vel superiores 
Internal . Thyro-arytenoidei posteriores, vel inferiores 
muscles ' Thyro-arytenoidei transversi, vel brevis 
Arytenoidei 
Ary teno- epiglot tidei 
^ Hyo-epiglottideus, vel azygos epiglottidis. 
Dissection. — The entire larynx, pharynx, and substance of 
the tongue having been removed from the head, should then be 
placed in a hollow block, and a quantity of crisp hair inserted into 
the upper opening of the larynx. Little dissection will be required 
in order to display the external set after the removal of the de- 
pressors of the os hyoides ; but to bring into view the internal set, 
the constrictors of the pharynx at their inferior origin, and the 
