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over the others. Though the explanation may be quite satisfactory, yet 

 it has struck me that perhaps another interpretation might be given in 

 the light of the present varieties. It might be that for each finger as 

 a separate individual member four muscles might be provided in a 

 typical hand, two dorsal interossei, and two palmar, the former as 

 extensors and lateralizers, the latter as flexors and lateralizers ; but the 

 fingers being grouped as in the human hand, and the extensor and flexor 

 action being for the most part monopolized by the long special muscles for 

 the purpose, the secondary or Moralizing function becomes paramount ; 

 and, as two muscles for each action would usually be unnecessary, a 

 suppression takes place of the superfluous dorsal and the palmar interossei. 

 Then perhaps the dorsal prominence of the third metacarpal is the 

 cause that the muscles which in the human hand become obsolete on 

 the dorsum are the adductors, but on the palmar aspect the opposite 

 set disappear. "We still retain a trace of the double nature of the dorsal 

 interossei in their bicipital origins, as I think the deduction arrived at 

 by Meckel may be with reason accepted, that the bicipital attachment 

 of a muscle is usually a sign of the lateral coalescence of separate parts. 

 If this explanation be true, these varieties would show the typical or 

 unaltered state of development, respectively, of each set of muscles. 



12. Glutseus quartus of Mayer and Haughton, (ilio-capsular of 

 Harrison). This muscle is not by any means a rare constituent of the 

 human body ; its existence I have noticed in many animals; and Professor 

 Haughton has furnished me with numerous instances in which he has 

 found it to be a distinctly existing element, as in the lion, kangaroo, 

 rhea, &c. In man it usually runs from the anterior inferior spine 

 of the ilium, and is inserted into the capsular ligament of the hip joint, 

 and sometimes into the anterior intertrochanteric line above the lesser 

 trochanter. It may be of use as a special tensor of the capsule, or as a 

 rotator outwards or abductor of the hip joint, and seems to correspond 

 with the infraspinatus secundus in the shoulder; it varies in degree of 

 development, and is present as frequently as the psoas parvus. 



13. The peronaeus quartus I have seen as a distinct muscle, arising 

 from about two inches of the front of the fibula, at the junction of the 

 upper three-fifths- with the lower two-fifths of the bone, above the 

 peronseus tertius, from which, as well as from the extensor digitorum 

 longus, in one case it was completely distinct, and in other instances it 

 was with facility separated. Passing under the annular ligament aloug 

 with the extensor digitorum longus, it was inserted tendinous into the 

 base of the fourth metatarsal bone. In one subject in which this muscle 

 existed, the peronaeus tertius was absent ; in another instance the two 

 tendons arose from the same muscle ; and I have seen this tendon de- 

 tached from the outer slip of the long extensor of the toes. In one 

 strong muscular subject the tendon of the peronaeus quartus was as 

 strong as the flexor carpi radialis tendon at the wrist. A slip somewhat 

 homotypical I found in the right forearm of a dingo, running from the 

 dorsum of the ulna to the fourth metacarpal bone. 



14. The slip called peronseus quinque, or the band extended to the 



