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fectly separate ; there is usually in the lower extremity an aberrant super- 

 ficial portion lying obliquely over the rest of the mass — the sartorius, 

 which in the upper limb is represented by a superficial portion (dorsi 

 epitrochlearis) lying over the triceps. This muscle in the lower 

 extremity is usually attached to the anterior superior spine of the ilium, 

 and passes to the inner side of the head of the tibia ; or as in the seal, to 

 the inner side of the patella, or into the fascia of the inner side of the 

 thigh for two-thirds of its length, as in the crocodile (Haughton, ''Pro- 

 ceedings of the Eoyal Irish Academy," 1865, p. 50) ; in some animals, 

 as the Hyrax, it is absent in the upper limb. This muscle is repre- 

 sented by the dorsi- olecr anal (usually called dorsi epitrochlear ) slip of 

 monkeys — found in the hare, rabbit, guinea-pig, and agouti, and many 

 other animals ; by a scapulo-fascial muscle in the pig, which 1 have 

 described before ( " Proceedings of the Eoyal Irish Academy," April, 

 1866), and which exists in the horse, and as a second latissimus dorsi 

 in Echidna. Beneath this, the second portion of the great extensor mass 

 is to be found, the rectus, represented in the upper limb by the long head 

 of the triceps, whose origin is from the basal bone in the neighbourhood 

 of the capsular ligament of the shoulder or hip, and often in both limbs 

 attached to the capsule itself. The insertion of this mass is central 

 and usually regular ; occasionally, as in the hinder limb of the ostrich, 

 varied by an extension into some lower muscle : the origin of this 

 muscle is marginal, but always inclined to the outer side, hence it is be- 

 neath the infraspinatus and teres minor above, and beneath the scansorius 

 and gluteus medius below : this covers over the deeper portions of the 

 muscle, a mesial, an outer and an inner, the former pair represented in 

 man by the outer head of the triceps in the arm, and by the cruraeus 

 and the vastus internus in the lower limb. The latter is of the same 

 type as the inner head of the triceps above, and the vastus internus 

 below ; there is usually a small bundle of muscular fibres beneath the 

 middle segment, inserted into the synovial membrane, the subcruraeus 

 of the lower limb, and the subanconeus of the upper : the latter is by 

 no means so constant as the former. The resemblances of these need 

 no remark. 



The flexor group of muscles consists usually of four elements, 

 sometimes of five ; these most usually are the two heads of the biceps, 

 and the two inner hamstrings in the lower limb, and the brachialis 

 anticus and biceps in the upper. Now, contrasting these, so as to find 

 their individual correspondences, we see that the shorter head of the 

 biceps femoris is the obvious representative of the occasional humeral 

 head of the biceps flexor cubiti. The coracoid origin beside this is the 

 probable homotype of the long head of the biceps, with which it agrees 

 in several respects — first, as its origin is from the ischiatic element of 

 the basal bone ; second, because its fibres are connected with the former 

 element when it exists in the upper limb, although, indeed, in the thigh 

 this union is by no means a necessary arrangement j for the femoral 

 head is inserted into the semi-tendinosus in the ostrich, and into the 



