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MR. J. C. GALTON ON DASYPUS SKXCINCTUS. 5." 1 



The muscle has hvo heads of origin, the larger of which is the more anterior — tin 

 smaller, which is about one-third of the former in rise, arising posterior to it, and imme- 

 diately in front of the acetabulum. The sciatic nerve passes along the thigh to its outer 



side. 



Henle 1 describes this muscle in Man as being made up of two portions at its origin. 

 Obturator internus. — Appears to be wanting, as might be expected, seen g that there is 



no lesser sciatic notch, the whole of that portion of the ischium which Intervenes between 



its tuberosity and what must be regarded as the homologue of its spine being articulated 

 with the sacrum. 



Cuvier, moreover, gives no indication of this muscle in his plates, but -talcs in h 

 'Lecons' 2 that in animals which have the ischium anchylosed with the sacrum (e.g* 

 Tamandua) a muscle coming from the external face of the ischium takes the place of tin 

 obturator internus and the ge nielli, 



Itapp 3 notices the existence in the Tamandua of The external obturator muscle, and of 

 a muscle which "appears to answer to the gemelli," but makes no mention of an obtu- 

 rator internus, or of a substitute for it. 



In the Ai, according to Meckel 4 , this muscle has left its position, and has become a 

 second obturator extemus, but smaller than the external obturator proper, under which 

 it is situated. A like arrangement exists in the Anteaier, which, moreover, pos se s ses 

 as does the Ai likewise, but one gemellus. 



Gemelli. — Both these muscles are present, though the muscle with which they are in 

 Man so intimately associated is absent. They are both delicate muscles, the anterior 

 being the most slender, in that it is about one-third of its fellow in size. The former is, 

 moreover, fusiform, while the latter is more or less fan-shaped, tapering from its origin 

 towards its insertion. 



Their origin is much further forward than in Man, owing to the great length of tin 



ischium. 



They arise immediately behind the posterior portion of the neck of the acetabulum, 

 just above the superior border of the thyroid foramen, and are inserted into the di ital 

 fossa of the great trochanter, immediately posterior or superior to the strong tendon of 

 insertion of the obturator extemus. 



Quadratus femoris.—Is an oblong muscle, of fair size, arising from the ramus of the 

 ischium, immediatelv below the adductor. It passes across to be inserted obliquely into 



e 



the posterior part of the rough ridge forming the anterior edge of the inner trochanter. 



Cuvier figures it in profile in one of his plates 5 . 



It is well developed, according to Meckel, in the Ai, but is absent in the Anteater 6 . 



Ilio-psoas — The two elements of this compound muscle appear to be early fused 

 together, and are inserted along the whole edge of the inner trochanter. The ilia* 

 element takes origin from the whole inner face of the ilium. 



Psoas parvus.— A long, slender muscle, which appears to arise from the outer side of 

 the posterior edge of the last dorsal and two first lumbar vertebra It passes down 



1 Loc. cit. p. 252. ■ Loc, cit. p. 502. 3 Op. at. p. 40. 4 Op. tit. p. 584. 



Op 



Op. cit. p. 586. 



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