THE MUSCLES. 



351 



second muscle (Fig. 314, ST), which, springing from the 

 ischium, passes downwards and ends in a fascia outside the 

 lower part of the flexor longus digitorum. 



The semi-tendinosus and semi-membranosus may, as in the 

 Seal, be represented by a muscle arising from the anterior 

 coccygeal vertebras and inserted into the tibia, some tendinous 

 fibres going to the plantar surface of the hallux. 



26. Of the MUSCLES OF THE LEG. The tibialis anticus, 

 even in Anthropoid Apes, may have the part going to the 

 hallux so distinct as to be reckoned a distinct muscle 

 sometimes called the abductor longus hallucis. It may be 

 unquestionably double, as in the Echidna. It may have a 

 double origin and a single insertion, as in the Agouti. It may 

 be inserted into the second metatarsal, as in Hyrax ; and 

 may be altogether wanting, as in the Pig. It is inserted 

 into the tarso-metatarsal bone in Birds, and is situate quite 

 on the inner aspect of the leg in Chameleo (Fig. 310). It 

 exists down to the Urodeles, being apparently double even 

 in Menobranchus. It may arise from the femur, as in the 

 Frog. 



Extensor proprius hallucis. This muscle may be altogether 

 absent, as in the Hare and Rabbit. It may even in man's 

 order (e.g. in Lemur) take origin from the tibia as well as 

 from the fibula. The tendon of the muscle may be inserted 

 into the second digit instead of into the hallux, which is the 

 case in the Echidna. Often this muscle is blended with the 

 extensor longus digitorum pedis. A muscle may exist in 

 Reptiles (e.g. in Chameleo) arising from the lower two-thirds 

 of the front of the fibula and inserted into the dorsum of the 

 second metatarsal ; and even in Urodeles (e.g. Menopoma 

 and Menobranchus) a small muscle arises from the lower 

 part of the fibula and goes to the hallux, or, in the absence of 

 this, to the second digit. 



The extensor longus digitorum pedis may spring from the 

 femur, as in the Pig, Hare, Hyrax, and Horse. Apart from 

 diminution in the number of the tendons resulting from the 

 atrophy of certain digits, the subdivision and distribution of 

 the ultimate tendons may vary even in the Primates. It may 

 end in two tendons only, going respectively to the second 

 and third metatarsal bones (as in the Iguana), or it may be 

 inserted exclusively into the third, as in Chamczleo Parsonii. 



The extensor brevis digitorum pedis is subject to great varia- 

 tions in extent and arrangement in different animals. It may 

 be altogether wanting, as in the Hare and Rabbit. It may 



