Zoological Society. 225 



Gluteus externus. — The external gluteus (gluteus medivs of Meckel), 

 as in most Mammalia, is smaller than the middle or internal glutei, 

 but is relatively larger in the Apteryx than in birds of flight, in which 

 it is described as the pyriformis by Cuvier. This muscle, however, 

 besides its origin from the outside of the pelvis, overlaps part of the 

 gluteus medius, and has its insertion into the femur at some distance 

 below the great trochanter, all of which are marked characteristics 

 of the glutceus magnus. Origin. It takes its origin from the superior 

 margin of the os innominatum, extends along an inch and a quarter 

 of that margin, directly above the hip-joint, and is chiefly attached 

 by distinct short tendinous threads, which run down upon the exter- 

 nal surface of the muscle : it rises also by carneous fibres from the 

 external surface of the innominatum for three lines below the superior 

 margin. Insertion. The fibres converge and pass into a tendinous 

 sheet, beginning on the external surface of the muscle half-way down 

 its course, which ends in a broad, flat, strong tendon, inserted into a 

 rising on the outer side of the femur nearly an inch below the great 

 trochanter. It abducts and raises the femur. 



Glutceus medius. — Origin. A large triangular, strong and thick 

 muscle, has an origin of three inches extent from the rounded an- 

 terior and superior margin of the ilium, and from the contiguous 

 outer surface of the bone for an extent varying from an inch to eight 

 lines. Ins. Its fibres converge to a strong, short, broad and flat ten- 

 don, implanted in the external depression of the great trochanter, 

 having a bursa mucosa interposed between the tendon and the bony 

 elevation anterior to the depression. 



Glutceus minimus. — Origin. It rises below the preceding muscle 

 from the anterior and inferior extremity, and from one inch and 

 three-fourths of the inferior and outer margin of the ilium, and con- 

 tiguous external surface, as far as the origin of the gluteus medius ; 

 also by some fleshy fibres from the outside of the last rib. Ins. These 

 fibres slightly converge as they pass backwards to terminate in a 

 broad flat tendon which bends over the outer surface of the femur, to 

 be inserted into the elevation anterior to the attachment of the glutceus 

 magnus. 



A muscle which may be regarded either as distinct, or a strip of 

 the preceding one, arises immediately behind it from half an inch of 

 the outer and inferior part of the ilium ; its fibres run nearly parallel 

 with those of the glutceus minimus, and terminate in a thin flat 

 tendon, which similarly bends round the outer part of the femur, to 

 be inserted into the outer and under part of the trochanter imme- 

 diately below the tendon of the glutceus medius. This muscle is 

 peculiar to the Apteryx, and the preceding portion, or glutceus mini- 

 mus, is absent in most birds. 



Use. — All the preceding muscles combine to draw the femur for- 

 wards, and to abduct and rotate it inwards. 



Iliacus internus. — This is a somewhat short thick muscle, of a pa- 

 rallelogrammic form, fleshy throughout ; rising from the tuberosity 

 of the innominatum in front of the acetabulum immediately below the 

 glutceus minimus, and inserted at a point corresponding to the inner 

 trochanter, into the inner side of the femur near the head of that 

 Ann. 8f Mag. N. Hist. VoLxi. Q, 



