454 APPENDIX. 



if the brachialis anticus were developed to the same extent as the 

 vasti and crureus ; the iliacus internus, in its origin, attachment, and 

 relations to the pubes, exactly corresponds in its relations to those 

 of the scapular portion of deltoid, if the hones of the shoulder were 

 made to assume the relative positions of those of the pelvis. The 

 homologue of the posterior margin of the spine of the scapula, 

 widened and hollowed out, forms, in this manner, the anterior sur- 

 face of the iliac bone, and the homologue of the scapular portion 

 of the deltoid passes forward over and in front of the homologue 

 of the clavicle. 



With reference to the homologue of the psoas in the shoulder, 

 it will at once suggest itself to the comparative anatomist, that the 

 psoas is represented by the levator humeri, more particularly by 

 that portion of it which is connected to the transverse processes of 

 the cervical vertebrae. In the feline Carnivora the levator humeri 

 passes down, in connection with the scapular portion of the deltoid, 

 in front of the clavicle, and reproduces in this manner an arrange- 

 ment in the shoulder exactly similar to that of the psoas, iliacus, 

 and pubis, in the posterior limb. It is also to be observed, that 

 the breadth of the anterior surface of the ilium is, in the greater 

 number of Mammalia, diminished so much as frequently to present 

 the form of a margin, while in the bird it has disappeared alto- 

 gether, as well as the muscle to which it gives origin. 



If the iliacus internus be the homologue of the scapular portion 

 of the deltoid, then we are at once led to the homology between 

 the pectineus and adductor longus in the posterior limb, and the 

 clavicular portion of the deltoid, and the clavicular portion of the 

 great pectoral in the anterior limb. 



The pectineus and the adductor longus pass from the pelvic 

 representative of the clavicle to the line leading down from the 

 lesser trochanter ; that is, from the attachment of the homologue of 

 the scapular portion of the deltoid. 



It is to be observed that the great tuberosity of the humerus 

 is the upper part of a ridge, which, extending down as the anterior 

 lip of the bicepital groove, widens out into the deltoid surface. 



Now, as the attachment of both portions of the deltoid, and also 

 of the great pectoral muscle, have been shown to have their homo- 

 logue in the thigh-bone, forced to the inner and back part of that 



