326 PEOF. r. G. PAESONS ON THE 



When the semitendinosus, caudo-f emoralis, and ecto-gluteus are 

 cut and reflected, the great sciatic nerve is exposed. Deep to 

 this is a muscle whicli rises from the same origin as, but deep to, 

 the semitendinosus, and after passing obliquely downward and 

 forward, is inserted into the middle of the femur. Probably the 

 name of caudo-femoralis profundus would best describe this 

 (see fig. 4). 



The Semimembranosus rises only from the tuber ischii, as is 

 usual with rodents, and is inserted into the tibia deep to the 

 internal lateral ligament of the knee. 



The Presemimemhranosits is quite distinct from the last and 

 is closely connected with the adductor mass. This I have already 

 pointed out (P. Z. S. 1894, p. 286) is a sciuromorphiue charac- 

 teristic. 



The Qimdratus Femoris is entirely fleshy, as in other Sciuro- 

 morpha. 



The JPectineus is inserted just below the lesser trochanter of 

 the femur. 



The Adductor longits continues the plane of the last downward 

 and is inserted just below it into about a third of the femur. 



The rest of the Adductor mass rises from the ramus and tuber 

 ischii, and is inserted into the lower two-thirds of the shaft of 

 the femur. 



The Gracilis (Adductor cruris) is a single broad muscle rising 

 from the symphysis and ramus of the pubes and being inserted 

 into the upper third of the shaft of the tibia. This single gracilis 

 has been shown to be characteristic of the Sciuromorpha as 

 opposed to the Myomorpha. 



The Tibialis anticus rises from the tibia only, and is inserted 

 into the innermost of the five metatarsal bones. 



The Extensor Longus Digitorum has the usual femoral origin 

 and is inserted into the outer four toes. 



The Extensor Proprius Hallucis rises from the middle third of 

 the fibula, and is inserted into the terminal phalanx of the hallux. 

 The full complement of Peroneal muscles is present ; viz., Pero- 

 neus longus, brevis, quarti digiti and qxiinti digiti. 



The Gastrocnemius and Soleus have the usual rodent appear- 

 ance, they form a twisted Tendo Achillis *. 



* See Journal of Anat. & Phys. vol. xxviii. p. 414. 



