﻿DR. J. MURIE ON THE THREE-BANDED ARMADILLO. l09 



Galton's ^ grapMc description of the condition and relations extant in D. 6-cinctm 

 answer admirably to Tolypeutes. 



The most interesting point is the Y-shaped elongation from opposite sides of the inner 

 dinsions to the xiphoid. What relation does it hear to the anomalous variety in human 

 myology the so-called *museulus sternalis/ * prsesternalis,' * rectus sternalis,' * ster- 

 nalis brutorum ' and ' thoracicus ' of various anatomists ? Professor Turner's observa- 

 tions^ and historical account embrace complete argument on the question. He himself, 

 with others, considers it a remnant of panniculus carnosus, as opposed to opinions 

 advanced of its being an upward continuation of the rectus abdominis, a do^mward 

 extension of sternomastoid, a muscle sui generis, or mayhap allied to the supra- or 

 stemo-costalis. From a study of the data, I am inclined to hold a middle view. In the 

 human subject it may retain a special name in favour of its variable nature and possible 

 junction of two different muscles and layers. To my mind Turner's excellent delinefi- 

 tions &c. prove that it has nothing to do with the supracostales (primus and secundus^), 

 whose plane is deeper and direction of fibres nearly at right angles. Again, it cannot 

 be confounded with rectus, since the latter, when produced to the foremost ribs (whether 

 aponeurosis or otherwise), passes beneath the supracostal *. Its transitory con- 

 nexions to tiie pectoralis major and obliquus extemus none have advocated as supporting 

 its claim to be a production of either ; nor do I think there are good grounds to justify 

 such an assumption. It may be admitted as unique in Man, forasmuch as it fre- 

 quently conjoins sternomastoid and external oblique &c. ; but this by no means implic^s 

 absence of its representative elements in animals. On the contrary, by its very Irre- 

 gularity is its composition best evinced. Where alone developed inferiorly (posteriorly, 

 " origin" of Turner), it is a true homologue and rudiment of the panniculus (" thoraco- 

 facien" of Cuvier), as Hallet, Turner, and Galton surmise; but its superior end, iji rela- 

 tion to sterno-mastoid, does offer similarity to the rearward prolongation of that muscle 

 existing in Tolypeutes and other forms— to wit, the opinion held by Bourienne, Tliiclc, 

 and Henle. The difficulty thrown out by Wilde and Turner of its lying on a plane beneath 

 the platysma myoides strengthens rather than weakens its tegumentary character ; for 

 in many mammals (I may specify the Manatee) an almost distinct sheet of the general 

 robe of the panniculus starts from over the sternum, passes forwards beneath the trans- 

 verse platysmal fibres en route to the malar arch. The latter anatomist's cases, figs. 4, 5, 

 and 6, are those that best uphold continuity with sternomastoid ; but should it be shown 

 hereafter that in verity, tendon or otherwise, it goes superficial to, and does not become 

 thoroughly fused with, the manubrial extremity of the sternomastoid, then undoubtedly 

 the musculus sternalis is none other than a remnant of the lower mammalian cutaneous 

 sheet. ' . " 



' L. 



capeiisis," Trans. Linn. Soc. vol. xxvi. p. 5C8 



An at 



Although the supracostal in animals is ordinarily single, yet a pair on each side are occaaionally met 



^tness Lemur catta, " Anat. of the Lemuroidea," Trans. Zool. Soc. vol. vii 



continuity 



sternalis, may this not have heen a develonment of eupracostal in apparent, not real, continuity with 



