﻿104 



MURIE 



ARMADILLO 



What has heen denominated psoas ligament, may be critically considered by others the 

 homolo-ue of a psoas parvus muscle. It certainly is altogether devoid of fleshy fibre ; 

 and moreover/there is an additional factor suggestive of the latter. This, for contrast, 

 then I shall regard as psoas parvus. It is a tiny slip posteriorly inside the so-caUed 

 hgament, and composed of slender fleshy fasciculi coming from the sides of the third and 

 fourth lumbar vertebrae, and inserted by a delicate tendon on the inner aspect of the 



ilium, just below the last. 



The muscle answering to the ilio-psoas of Galton and psoadiliacus of Macahster is 

 clearly of a compound character in Tolypeutes. That moiety which best answers to a 

 psoas magnus covers the ventral surface of the ilium by a layer of flesh, and is inserted 

 by a strong tendon on the upper point of the lesser femoral trochanter. The narrower 

 outer segment, or iliacus, springs more from the edge of the bone, and descending along- 

 side the first, in close proximity to it and the rectus femoris, is muscularly fastened in 

 front of the lesser trochanter below the femoral neck. 



An obturator internus is said to be wanting in Dasi/pm^ and Chlamy doplioms^ ; but in 

 Tolypeutes a thin fleshy sheet covering the interior surface of the ischium around the 

 obturator is evidently the muscle in question, in spite of the difficulty raised, viz. ossifica- 

 tion and obliteration of the lesser sciatic notch. There obtains likewise a well-developed 

 obturator extcrnus agreeing pretty well with that of Dasypus (Galton), and not so 

 bound up with the gemelli &c. as in Chlamydophorus (Hyrtl). 



T have already made my remarks on the pyriformis, and here, along with the obturators, 

 specify an anomalous sacro-pelvic muscle. It may be (and this is not improbable) a 

 deep layer or division of the pyriformis. In this case it is so distinctive that I class 

 it separately among the inner pelvic muscles, and append the cognomen of oblique sacral 

 to it, the rather to mark its presence than denote its importance. Its origin is from the 

 pelvic surface of the narrower portion of the sacrum, and in a broad fleshy layer fills up 

 the great sacrosciatic space. Its posterior border impinges upon upon the infracaudal, 

 the sacrococcygeus, and the obturator internus. The sacrosciatic nerve escapes at its 

 fore border and lies on its dorsal surface, separating it therefore from that previously 

 described as a pyriformis. Its fibres and those of the latter do not coincide in direction, 

 but pass at an acute angle to each other. 



This oblique sacral certainly does not belong to the category of the ordinary caudal 

 muscles, neither does it answer to the obturator tertius met with by Mivart and myself 

 in Hyrax capenms\ Without being absolutely identical, it best harmonizes with the 

 lygeus of human anatomy, and partially with the same muscle in the Hyrax. 

 Depressores caudse.-Of these, three pairs are easily made out, their fleshy bellies being 

 fuUy developed though flat. That to which the name infracoccygeus or infracaudal is 



tJIki 



plicablc 



^^^^^^ ^^® «f the sacrum posterior to its narrowing at the 

 space; the middle sacral artery runs between the muscles of opposite sides. The muscle 

 docs not become tendinous until reaching the chevron bones, thence proceeds within 

 the mail-clad tail for about half its length 



Tnuw. Linn. Soc 



vol . xxvi. p. 551 and Ann 

 346, figs. 9, 10. 



Hyrtl, I c. p. 39. 



