544 
destined to act upon the skin itself or upon 
cuticular structures of very diversified shape, 
which are occasionally developed in different 
regions of the body, and not unfrequently ap- 
propriated to the performance of important 
duties. In those quadrupeds that have their 
backs covered with strong spines, such as the 
Echidna, the Porcupine, and the Hedgehog, 
the cutaneous muscles, usually named panni- 
culus carnosus, are met with in their most com- 
plete form, since in these creatures every quill 
or spine is moved by muscular bands con- 
nected with its base, that serve to erect or de- 
press it at pleasure. The crests and other 
moveable appendages tu the skin met with 
among Birds, are equally furnished with the 
means of motion by strengthening particular 
parts of the muscular apparatus in question. 
In Reptiles, on account of the nature of their 
corneous integument, the muscles of the skin 
are but slightly developed, or indeed most 
generally are not to be detected. - But in Fishes 
they once more present themselves, under a 
novel and most important aspect. The azygos 
fins in these aquatic Vertebrata are, as is else- 
where shewn (vide Pisces), derivations from the 
exo-skeleton, and consequently all the slips of 
muscle, that act upon the individual rays of 
the dorsa!, caudal, or anal fins, however ano- 
malous their nature may appear without such 
a key to their real character, are obviously 
merely portions of the tegumentary system of 
muscles here elevated into an importance not 
witnessed .in other animals, where the exo- 
skeleton is less decidedly appropriated to the 
purposes of locomotion. 
8. The muscles whereby vocal sounds are 
modulated, are equally entitled to be looked 
upon as a distinct and superadded system only 
conferred upon certain races of Vertebrata, and 
that under very various conditions. In Fishes 
these muscles are of course absolutely wanting, 
and even amongst the air-breathing Reptiles 
they are so imperfectly developed as scarcely 
to be regarded as vocal organs. But in Birds 
and Mammalia they assume a higher form, and 
are variously located and more or less nume- 
rous in exact proportion as the voice is per- 
fected. In Birds, indeed, the vocal muscles 
are principally se at the thoracic extremity 
of the trachea, but in Quadrupeds and in Man, 
at the opposite end, the whole machinery being 
thus so completely altered that even analogies 
between the different sets of muscles are not 
easily pointed out. 
9. The diaphragm is an apparatus exclu- 
sively conferred upon the Mammiferous Ver- 
tebrata, since in these only is the thoracic 
cavity separated from the abdomen by a mus- 
cular septum. 
10. The muscles of the tongue must like- 
wise be regarded as forming a distinct group, 
increasing in complexity and extent of motion, 
in proportion as the organ to which they belong 
assumes ter importance, either as an in- 
strument for the prehension of food, or as an 
agent in mastication. 
11. The ocular system of muscles may be 
divided into those which act on the eyeball, 
MYRIAPODA. 
and those employed in moving the palpebral 
appendages. The former when complete con- 
sist of four recti, two obliqui, and the choano 
or suspensary muscle, which not unfrequen 
is distinctly divided into four. The reedi ; 
invariably met with and present few variat 
worthy of notice. The obliquus superior 
Mammals passes through a pulley, 
not the case in other Vensbedtl while 
choanvid muscle is principally met w 
Quadrupeds. 
The muscles of the eyelids are mos 
fectly developed in Birds, in which dis 
muscles are appropriated to the movemen 
the upper and lower eyelid as well as to 
nictitating membrane, which in the f 
races has a proper set of muscles appoi 
to draw it over the eye not met with in ot 
classes. > 
12. The muscles of the auditory ppa 
become fully developed only in the mamm 
rous ear, where four little muscles are in 
riably found connected with the ossicula 
tus, as in the human subject. The mu 
appointed for the movements of the exte 
ear are, however, in many Quadru 0 
more numerous than in Man; in iy 
human ear they merely exist, in a radimen 
condition. 2 
13. The nasal apparatus has likewise a 
tem of muscles of its own, although th 
stances in which it is met with in any 
like a complete state of developement are ¢ 
paratively rare. In Fishes, Reptiles, and — 
these muscles, indeed, can hardly be sa 
exist; and even in the generality of Man 
they are feeb!e and unimportant. It is o 
the proboscidean species, that the nasal mi 
assume their full complexity, and the tr 
the elephant is in modern times the oi 
ample, wherein the anatomist can cont 
them. 
14. The muscles of the generative § 
are only found to exist, as a distinct set, | 
Mammalia, as in these alone is the 
canal complete, and a perfect ejaculat 
paratus given. y 
Thus, therefore, we may learn from thi 
survey, that so far from finding in the: 
frame the fullest and most elaboratel 
structed examples of the various divis 
the muscular system, or, in other word 
pical condition of that part of the 
economy, the human anatomist, in mai 
stances, has only an opportunity of ex: 
the vestiges or rudiments of organs, the 
lower animals attain to a far more e0 
developement. 
(T. Rymer J 
MYRIAPODA, (from the Greek 
ten thousand, i. e. numerous, and groug,. 
the name of an important and highly i 
ing class of articulated animals, mtern 
in their structure and ap ce b 
the Annelidans and the Insecta, pr 
so called; approximating the former in 
worm-like form of their bodies, which 
composed of a great number of rings or 
