i82 ANATOMY OF CERTAIN MEGAPODBS. 



transverse processes of the two last coccygeal vertebrae, 

 and is inserted into the linea aspera of the femur at 

 about one-third of its length from the trochanter." In 

 ni}^ specimens I have found the insertion exactly as 

 stated by Garrod, but when the muscle is traced out 

 towards the tail the arrangement is found to differ re- 

 markably from that laid down by him. The muscle on 

 each side is found to spread out into a thin aponeurotic 

 sheet, the two uniting and covering the lower side of 

 the muscles of that region. The shape of this muscle, 

 remarkably enough, varies in the two genera. In the 

 Brush Turkey it is long and ribbon-like, while in 

 " Lipoa " it is much expanded and thin, so that its 

 centre part comes to be leaflike. This latter condition 

 in " Lipoa " may, however, be due to the pressure of 

 overlying muscles in preservation. The accessory head, 

 however, agrees in both genera in being large and fan- 

 shaped, rising along a fairly extensive line posterior to 

 the ischiatic foramen, covering in this position the lower 

 half of the hollow, which lies external to the ilio-ischi- 

 atic crest. Centrally this muscle is thinned, consisting 

 only of an aponeurosis, through which can be seen the 

 tendon of M. obturator externus. 



The arrangement of the semimembranosus is inte- 

 resting in these birds. In " Gallus " this muscle rises 

 from the outer edge of the ischium, but its origin does 

 not extend so far back as to completely cover the ischio- 

 pubic foramen. In " Catheturus " and " Lipoa," how- 

 ever, this foramen is coinpletely covered, so that with 

 the lengthening of the origin the muscle comes to be 

 fan-shaped. In company with the semitendinosus, it 

 forms the posterior contour of the thigh. 



M. ambiens has much the usual insertion, bending 

 round the knee over the patella, to become merged with 

 the head of M. perforatus digiti iii., but its origin is 

 worthy of comment. It is not, as usual in birds, a thin, 

 spindle-shaped muscle ; but owing to the fact that it 

 arises from both the pectineal process, and some small 

 portion of the bone behind it, it comes to be triangular. 



The muscle representing the pyramidalis, called by 

 Gadow the ilio-femoralis externus, and by Owen and 

 Selenka, the glutaeus externus, is also present in the 



