378 THE ANATOMY OF VERTEBEATED ANIMALS. 



lares, arise from the middle caudal vertebrae, and, after re- 

 ceiving fibres from the ventral region, end in the dorsal mar- 

 gins of the orbicularis. 6. Tvi^o muscles attached to the 

 pinnae of the ears (auriculo-orbiculares) pass backward to the 

 orbicularis on each side. 



On the ventral aspect are certain muscles which assist the 

 orbicularis : 1. Two broad muscles (sterno-faciales) arise in 

 the middle line, over the anterior part of the sternum, and 

 pass outward and forward to the sides of the lower jaw and 

 the integument of the face and ears. Muscular slips fi-om 

 these are sent up over each shoulder to the orbicularis. 2. A 

 humero-abdominalis arises from each humerus beneath the in- 

 sertion of the pectoralis major, and, passing backward over 

 the sides of the abdomen, these become connected with the 

 ventral edges of the orbicularis. The external fibres of these 

 muscles are continued round the ischial regions to the coccy- 

 geo-orbicndaris ; the internal fibres pass to the prepuce, and 

 over the middle line of the abdomen, in front of it. 3. A hu- 

 mero-dorsalis arises from the humerus close to the foregoing, 

 and, passing upward and backward through the axilla, spreads 

 out in the mid-dorsal integument and the orbicularis. 



The contraction of all these muscles must tend to bring 

 togther the edges of the integumentary bag, and to tuck the 

 head, tail, and limbs into it. 



In the myology of the limbs the following points are note- 

 worthy : The supinator longus, pronator teres, and palmaris 

 longus, are absent. The palmaris brevis is present. A single 

 muscle takes the place of the extensor secundi intern odii polli- 

 cis and extensor indicia, and sends a third tendon to the m.id- 

 dle digit. The extensor minimi digiti supplies the other two 

 digits. The flexor perforans and flexor pollicis longus are rep- 

 resented by five distinct muscular heads, each with a tendon 

 of its own ; but all the tendons unite in the middle of the fore- 

 arm, and the common tendon again subdivides into only four 

 slips, the poUex receiving no tendon. There are no Imnbrica- 

 les. The pollex has only a rudimentary _7?ea;c»r brevis and au 

 abductor. The other digits have each two interossei, ot flex- 

 ores breves, inserted into the raetacarpo-phalangeal sesamoids. 



In the leg, the solsus has only a fibular head, and iheflexoT 

 brevis digitorum arises wholly from the calcaneum. 'Yhxi flexor 

 hallucis and flexor pierforans have a common tendon, which, 

 In the sole, divides into five tendons, one for each digit. 

 There are no lumbricales, nor flexor accessorivK. The tibialis 

 posticus seems to be represented by twc small muscular bel- 



