328 llev. S. Haughton on the Muscular Anatomy 



under which it passes to be inserted into the outer and under 

 side of the outer tarsal bone. O03 oz. 



8. M. plantaris ? (a?). Origin, double: from rectus femoris 

 and from agitator caudse. Insertion : having become partially 

 blended with the outer gastrocnemius, it is inserted into the os 

 *alcis and under surface of the plantar fascia. 0*04 oz. 



9. M. peronseus longus (y). Origin: from the shaft of the 

 fibula and from the tendon of the biceps femoris [d). Insertion: 

 into the outer tarsal bone, uniting with the tendon of the 

 gastrocnemius. 0*03 oz. 



10. Mm. tibialis anticus and extensor digitorum communis. 

 Insertion : into the tarsal ends of first, second, and third meta- 

 tarsal bones. 0*11. 



The interlacing of muscles in the thigh and leg of the Croco- 

 dile, just described, is very remarkable, and more complicated 

 even than that found in the Ostrich ; and at first I was dis- 

 posed to think that it threw some doubt on the explanation I 

 had given previously of the reason for such an arrangement in 

 the bird's leg. In the case of the Ostrich, the necessity for 

 strict simultaneity of action was made evident by the great force 

 of the muscles employed, and the great delicacy of the bones on 

 which they had to act. What could there be, in the case of the 

 Crocodile, to correspond to such a peculiarity in the case of the 

 Ostrich ? After some careful dissection, I found the ready 

 answer to my question in the remarkable muscle which I shall 

 now describe. 



On clearing away the superficial muscles of the thigh and 

 tail, I found the enormous mass of muscle, figured at b, fig. 13, 

 PL XVI., which acts as the chief and powerful extensor of the 

 thigh : — 



11. M. extensor femoris caudalis* (b). Origin : from the 

 transverse and inferior spinous processes of the caudal vertebrae, 

 from the third to the fifteenth inclusive. Insertion : into the 

 back of the upper part of the femur, and into a great round 



* This remarkable muscle is noticed and accurately described by Meckel 

 in torn. iii. }). 152, 153 of his ' System der vergleichenden Anatomie,' Halle, 

 J.828; but it is very strange that he transposes its origin and insertion, 

 and seems not to have had any idea of its rial use. It is regarded from 

 his point of view as a descriptive anatomist, and without the remotest 

 reference to its final cause. He says, " Der zvveite, tiefere, vveit dickere 

 Musk el ist von dem ersten [the superficial muscle of the tail] wie einer 

 breiten Binde umgeben, entspringt mit zwei ganz getrennten ; einer weit 

 kurzern, breiten Sehne oben von den hintein Fliiehe des Obcrschenkel- 

 beines ; durch eine weit langere, sehlanke, unten zwischen den beiden 

 Gelenkknorren desselben Knochens, und setzt sich an die ganze Seiten- 

 fliiche der untcrn Dornen, so wie der Zwischendornenhaut und die untere 

 Flache der Wurzeln der Querforts'atze." 



