312 MR. R. H. BURNE ON THE [Apr. 18, 



Piobi-ischio-femoralis externvjS (text-figs. 65, 66. 14). — Origin : 

 from the whole ventral surface of the pubis and epipubis between 

 the insertion of the epipubic pait of the rectus abdominis and the 

 origin of the pubi-femoralis and the obturator foramen ; from 

 the venti-al surface of the ischium between the obturator foramen 

 and the mid-line ; and from the dorsal surface of the ischium and 

 the root of the ilium. Insertion : upon the tuberosities of the 

 femur, just distal to the posterior third of the neck. 



The part of this muscle that arises from the dorsal surface of 

 the ischium and from the ilium is probably the representative of 

 Gadow's pubi-ischio-femoralis posteiior. 



This muscle, with the pubi-ischio-femoi^alis internus and the 

 ilio-femoralis, forms a thick continuous muscular sheath around 

 the hip-joint. 



Extensor longus digitorum (text-fig. 67. 16). — Oi'igin : from 

 the external condyle of the femur covered by the insei-tion of the 

 extensor ilio-tibialis. Insertion : by tendinous expansion to the 

 extensor surface of metatarsals TV. and Y., in conjunction with the 

 peroneus ; by tendinous slips between each of the four inner toes 

 on the level of the metatarso-phalangeal joints ; and by a strong 

 tendon to the inner margin of the head of the first metatarsal. 



The insertion is less definite than that described for this muscle 

 in other Chelonia. 



Tibicdis anticus (text-figs. 65 & 67. 1 7). — Origin : from the upper 

 two-thirds of the inner (radial) margin of the radius. Insertion : 

 upon the extensoi- surface of the head of metatarsus I. and also 

 by a tendinous expansion to the fibrous tissue on the fiexor 

 sui'face of the ankle. 



/•ero^teits (text-fig. 67. 18). — Origin: from the distal half of 

 the extensor sui-face of the fibula and fi-om the extensoi- surface 

 of the fibular side of the tarsus. Insertion : upon metatarsals lY. 

 and Y. The i-adial side of this muscle is continuous with the 

 deeper pai'ts of the extensoi- longus digitorum. 



Gastrocnemius (text-fig. 65. 20). — Origin : from the inner 

 condyle of the f emui- and f I'om the innei' and flexor surfaces of the 

 shaft of the tibia, around the insertion of the pubi-tibialis. 



At the heel the muscle is transformed into a dense sheet of 

 fibrous tissue, from which arise in the sole of the foot the super- 

 ficial (perforated) flexors of the digits. 



The gasti'ocnemius has also direct attachments to the base of 

 metatarsal I. and to metatai'sal Y. 



Perforated flexors (text-fig. 65. 20 a). — Origin : from the fibrous 

 expansion of the gastrocnemius. Insertion : into the fii-st phalanx 

 of digits I. to lY. These small muscles surround the tendons of 

 the deep flexor and are inserted directly into the peiiosteum. 



Flexor longus digitoruin (text-figs. 65 & 66. 21). — Origin : 

 from the hinder (flexor) surface of the internal condyle of the 

 femur, from the whole flexor surface of the fibula, and from the 

 proximal half of the fibular side of the tarsus. 



