SOLIPEDA. 



731 



planted into the anterior surface of the base of 

 the metatarsal or cannon bone, so as to be 

 simply an extensor of that portion of the foot 

 which in these animals is usually misnamed 

 the leg. 



The tibialis posticus is altogether wanting 

 in the Solipeds, as also in the Ruminantia and 

 the hog- tribe. 



The three peronei are, in the horse, repre- 

 sented by a single muscle, the tendon of which 

 becomes conjoined with that of the long ex- 

 tensor of the digit, with which, when in action, 

 it co-operates. 



Muscles inserted into the digit. The ab- 

 ductors and adductors * are the abductor pol- 

 licis, the adductor obliquus pollicis, the ad- 

 ductor transver sails, the abductor minimi digiti, 

 and the interossei, 



The flexor muscles in the horse are ne- 

 cessarily reduced to a state of extreme sim- 

 plicity ; the short flexor communis is entirely 

 wanting ; the plantaris, as described above, 

 considerably increased in importance, has a 

 double insertion into the base of the great 

 pastern bone, and presents a similar disposi- 

 tion to that of the flexor perforatus in digitate 

 quadrupeds, while the flexor communis longus 

 pcrforans, here reduced to a single tendon, ap- 

 propriated to the solitary toe, passes on as 

 usual to be inserted into the last phalanx. 



The flexor longus pollicis exists both in the 

 Ruminantia and Solipeda, notwithstanding the 

 total absence of a thumb in these animals ; 

 but, instead of its usual destination, it here be- 

 comes affixed to the tendon of the flexor com- 

 munis perforans, to which it forms a powerful 

 auxiliary. 



The extensor muscles of the toes in all 

 digitate quadrupeds, provided with a repre- 

 sentation of the great toe in the human 

 foot, resemble those of man : in other animals 

 there are some peculiarities that require no- 

 tice. In the Quatlrumana, the three muscles 

 found in the human foot are present ; but in 

 addition to these there is a proper abductor of 

 the thumb (adductor, as it would be called by 

 the anthropotomist), situated upon the inner 

 side of the extensor pollicis longus, of which 

 no traces exist in mankind. 



Where the inner toe is wanting, as in the 

 dog and the rabbit, the extensor pollicis is 

 likewise deficient. 



In the cloven-footed quadrupeds there is a 

 proper extensor to the inner toe representing 

 that of the thumb, and the peroneus longus, 

 which is inserted into the external toe, per- 

 forms the office of extending that also : there 

 is moreover in Ruminants a long abductor of 

 the thumb, the tendon of which is inserted 

 close to that of the tibialis anticus 



In the Solipeds, the extensor communis 



* In comparative anatomy, owing to the perma- 

 nently prone condition'of the hand and footof animals, 

 it is impossible to employ the terms abductor and ad- 

 ductor, external and internal, &c., in the same sense 

 as the anthropotomist : by abductors we therefore 

 mean muscles which separate the external from the 

 middle fingers, by adductors those which bring the 

 fingers more closely together. 



(peronco-sus-ongiiicn) terminates in a single 

 tendon, which is inserted into the dors urn 

 of the last phalanx of the foot : it receives, 

 however, in transitu, a few fleshy fibres de- 

 rived from the cannon bone, which repre- 

 sent the extensor brevis of unguiculate quad- 

 rupeds. 



In the Solipeda, as might be expected, the 

 abductors and adductors of the toes are en- 

 tirely wanting. 



Muscles ivhich act immediately upon the 

 lower jaw. These are the masseter, the 

 temporal, and the two pterygoidei, which in 

 all quadrupeds have the same general arrange- 

 ment as in human beings. 



Muscles of the os hyoides. The os hyoides 

 of the Solipeds is constructed in accordance 

 with a plan common to the Ruminants, and 

 many Pachydermatous quadrupeds. Its body 

 is arched and broad, presenting in the middle 

 of its fore part a simple tubercle, and a toler- 

 ably long apophysis. It is consolidated with 

 the superior cornua, which together form a 

 very open arch. The single piece forming the 

 anterior cornu is articulated to a rounded 

 tubercle, situated just in front of the union 

 between the posterior cornua and the body of 

 the os hyoides, so as to admit of a consider- 

 able degree of motion in this joint. At its 

 termination it is connected to the styloid pro- 

 cess, which is very long and slightly forked. 



The movements of the os hyoides are ef- 

 fected by numerous muscles, derived from 

 several sources, the general arrangement of 

 which, in most quadrupeds, conforms pretty 

 nearly with what occurs in the human spe- 

 cies. 



The sterno-hyoideus exists in all quadrupeds, 

 or, at least, is represented by a muscle of cor- 

 respondent effect, derived from the sternum. 

 In the Solipeda and in Ruminants, the sterno- 

 hyoideus and the sterno-thyroideus form but 

 a single muscle, which divides, to be inserted 

 into both the larynx and os hyoides. 



The omo-hyo'ideus in the horse is a very 

 strong muscle, resembling in its origin that 

 of the human subject ; but in some rumi- 

 nants, as, for example, in the sheep, the ana- 

 logue of the omo-hyoideus is derived from 

 the transverse processes of the inferior cer- 

 vical vertebra?. 



The genio-hyoideus and the mylo-hyoideus 

 have nearly the same arrangement in all rnam- 

 miferous quadrupeds. 



In the horse, all three of the above muscles 

 are present. The stylo-kyoideus furnishes a 

 sheath to the longer portion of thedigastricus, 

 and extends from the furcate extremity of the 

 styloid bone to the base of the posterior corner 

 of the os hyoides : this is the " grand cerato- 

 hynidien " of Gerard. There is also a '' ccra- 

 toidicn lateral" (cerato-hyoideus) of Girard, ex- 

 tending between the corner of the os hyoides 

 and that of the thyroid cartilage. 



Thirdly, there is the niastoido-styloidcus 

 (stylo-hyoidien of Gerard), a short thick 

 muscle, derived from the long pyriform apo- 

 physis of occipital bone, whence it descends 

 towards the angle of the styloid bone, into 



