MYOLOGY OF THE ORNITHORHYNCHUS. 163 



position, with a femoral head, being an. accident of higher mammals. 

 The rectus, as usual among lower beasts, is discrete from the vasti; 

 these are blended together, with no evident crurcBus. The sartorius is 

 a flexor cruris, and, therefore, not in its normal oflice ; but it is inter- 

 esting to note, that its origin is relegated to the pelvis, and placed 

 lower down than in some animals, as marsupials, above this mono- 

 treme ; whereas, a higher, even a vertebral origin would have been 

 anticipated, in view of the animal's ornithic tendency. The motions 

 of the leg at the knee-joint, and actions of the muscles, will be noted 

 after the special descriptions. 



(a'. — From the body; "long.") 



We cannot demonstrate anj^ satisfactorj^ distinction between the ec- 

 toglutseus and the "flexor accessorius a cauda ad tibiam tendens," nor 

 between this last and the " intertibialis." With howmuchsoever dif- 

 ference in their origin, course, and function, the three blend in some 

 or another part of their extent. They form collectively an enormous 

 flexor cruris, effecting a powerful backward. pull (extension) of the 

 whole limb. Ectoglutfeus is also an outward rotator and abductor 

 of the limb; the caudal muscle a direct retroductor (and flexor cruris) ^ 

 while the slip passing from one tibia to the other, is an adductor draw- 

 ing the heels together under the tail, besides being a flexor cruris. 

 The details of this singular arrangement, which probably, from its 

 advantageous traction, acts more powerfully, for its size, than any 

 other muscular apparatus of the limbs of mammals, are these : — 



Ectoglutseus arises along the median line over the back of the sa- 

 crum and several anterior coccygeal vertebrae, in apposition with its 

 fellow, in a straight line from the apex of the ilium dowijward to a 

 point on the tail opposite the oingiu of the panniculus. Except in be- 

 ing overlaid by the last named, it is wholly superficial, resting above 

 upon the other two glutei, the pyriformis, and the dorso-lateral caudal 

 extensor; farther down, lying upon the last mentioned, and part of 

 the biceps, from the origin of which, however, it is separated by the 

 width of the tail at the part. The upper fibres run very obliquely 

 backward ; the others have successively more and more transverse di- 

 rection, and finally the lowermost ruu outward and a little forward. 

 At the posterior extremity of origin occurs an interval, equal to the 

 distance between the spinous and the transverse pi-ocesses of the coc- 

 cygeal vertebra; ; then a stout bundle of fibres — t]\G flexor accessorius — 

 takes fleshy origin from the tip of the transverse pi'ocesses of two or 

 three vertobrjc, and soon blends with glut;x;us proper. Erom the an- 

 terior border of flexor accessorius, intertibialis becomes diff'erentiated 

 about an inch from the leg, and passes directly transverse across the 

 tail below, rather more than an inch in front of the anus, to. be con- 

 tinuous with its fellow of tlic other side; it is attached to the pannic- 



