280 



KEPTILIA. 



surface of the pubis, confounding its anterior 

 margin with that of the glutaeus medius. The 

 obturator externus (adductor of Bojanus) 

 arises by two portions, one coming from the 

 pubis, the other from the ischium ; their two 

 tendons unite to form a broad tendon, which 

 is inserted into the two trochanters. 



The adductors of the thigh do not arise 

 from the pubis, but from the ischiadic portion 

 of the symphysis. 



A muscle, the analogy of which it is diffi- 

 cult to recognise, arises from the upper sur- 

 face of the pubis, and goes to be inserted by 

 a strong tendon at the side of the iliacus 

 (iliacus internus of Bojanus, surpubien of 

 Cuvier). In the turtles there is no iliacus, 

 and the suprapubic muscle divides into two 

 fasciculi, the external of which goes to the 

 knee, and joins the rectus of the thigh. 



Muscles of the Leg. The muscles of the 

 leg are more recognisable than those of the 

 thigh. 



In the land-tortoises these muscles are the 

 triceps ; the sartorius, which is divided into 

 two portions ; the semimembranosus, which 

 has a, large accessory slip derived from the 

 coccyx; the rectus anticus, which is situated 

 slightly internally, has an origin from the ex- 

 ternal ramus of the pubis, and is connected 

 with the articular capsule of the knee joint ; 

 the gracilis is confounded at its origin from the 

 ischium with the adductors of the thigh, but 

 it separates from them, and is inserted at some 

 distance from the head of the tibia. In the 

 turtles the musdes are not so thick as in the 

 land-tortoises ; the advanced position of the 

 pubis gives to the anterior rectus great force 

 in extending the thigh and the leg, for it is 

 inserted into the knee almost at a right angle. 

 The biceps and the semimembranosus arise 

 from the coccygeal region only. 



In the terrestrial tortoises the movements 

 of the foot upon the leg, and of the different 

 parts of the foot one upon the other, are very 

 limited, and consequently the muscles which 

 execute them are indistinct. 



There is but one peroneus, which is con- 

 founded by one of its margins with the ex- 

 tensor communis, and which is inserted into 

 the os calcis and into the cuboid. 



The gastrocnemius externus alone takes its 

 origin from the femur ; the gastrocnemius 

 internus arises from the tibia and joins itself 

 to the solaeus. This latter is divided into 

 three portions, one external, one median, the 

 other internal. These muscles, in conjunction 

 with the peronei and the long flexor of the 

 toes, form beneath the foot a thick ten- 

 dinous mass ; they extend the foot upon the 

 leg, and flex the latter upon the thigh ; but it 

 is next to impossible to distinguish the dif- 

 ferent portions. 



The tibialis anticus is distinct. 



In the turtles which have the foot, like the 

 hand, flattened into the shape of an oar, the 

 gastrocnemii are disposed as in the land- 

 tortoises, and the soleus is equally strong. 

 There exists, moreover, a slender plantaris 

 longus, which arises from the external tube- 



rosity of the femur by a long round tendon, 

 and which terminates in a broad expansion, 



Fig. 200. 



Myologyofthe Tortoise. (After Bojanus.} 

 119, tibialis posticus ; 120, interosseus cruris ; 

 122, interossei digitorum pedis dorsales; 123, in- 

 terossei digitorum pedis plantares. 



which is inserted partly into the os calcis, and 

 partly into the plantar fascia. This muscle 

 is from its position an adductor of the foot. 

 The tibialis anticus preserves its ordinary re- 

 lations ; but the tibialis posticus runs from 

 without to within, and its tendon becomes 

 lost in the plantar fascia. 



The toes of the Chelonians not having 

 more flexibility than their fingers, the muscles 

 of the foot are much confused. The extensor 

 communis longus digitorum, as in all other 

 reptiles, only reaches as far as the bones or 

 the metatarsus. The extensor brevis alone 

 reaches to the phalanges of the toes. 



There is, however, a proper extensor for 

 the great toe, which arises from the inferior 

 extremity of the fibula, an abductor of the 

 little toe, and interossei, which latter, as in 

 mammalia, are both adductors and abductors. 



In the turtles the extensor communis 

 spreads out as it approaches the toes, and 

 forms a broad aponeurosis, which co.vers the 

 whole foot. 



The extensor longus, and the abductor of 



Fig. 201. 



Myology of the Tortoise. (After Rojanus.) 

 117, tendons of the flexor longus digitorum ; 

 118, flexor brevis digitorum pedis. 



the inner toe, arise from the inferior extremity 

 of the fibula, and are inserted into the meta- 

 tarsal bone that supports this toe, as well as 

 into the first and second phalanges. 



Another muscle, which also arises from 

 the inferior extremity of the fibula, is in- 

 serted into the whole length of the metatarsal 

 bone of the fifth toe, and upon its first pha- 

 lanx : it is both an extensor and an adductor. 



