1894.] ANATOMY OP ORNITHORHYNCHUS. 703 



Extensor ossis metacarpi pollicis. — Arises chiefly from ulna ; 

 slightly also from radius. It is inserted, in usual position, into 

 base of first metacarpal bone. There is a tendinous band arising 

 from the cuneiform, which crosses the back of the carpus to join 

 the ulnar margin of the tendon. 



Myology of Manus. 



There is a small short muscle of the thumb, which is most 

 probably a combined flexor and abductor. There is a small muscle 

 passing to the little finger, which appears to be an abductor. 



Palmar inter-ossei. — Are fairly well marked and are three in 

 number. 



Muscles of the Posterior Extremity. 



Gluteus maximus. — Is a large flat muscle, which arises from the 

 posterior part of the crest of the ilium, from the sacral, and upper 

 eight caudal vertebrae. It is inserted into the lower end of the 

 tibia, this part being closely united with the inter-tibialis, and into 

 the sole of the foot, this portion going partly to os calcis and 

 partly to bone supporting the heel. The muscle has a very 

 similar origin and insertion in Echidna \ Meckel mentions its 

 attachment into the bone supporting the heel in the male. 



Beneath the gluteus maximus is a muscle which arises from the 

 first four caudal vertebra?. It is inserted into the femur about its 

 middle, just below the gluteal ridge. This deeper portion is 

 supplied by a branch from great sciatic. This is the muscle 

 described by Meckel as medius ; Mivart, too, in Echidna describes 

 a muscle having a similar position. The next-mentioned muscle 

 they both look upon as minimus. Mivart, however, mentions that 

 the muscle described above may represent a deep part of maximus. 

 Its insertion would point to that conclusion. Coues describes this 

 muscle as pyriformis : neither its origin nor insertion would 

 indicate that it corresponds to the ordinaiy pyriformis. 



Gluteus medius. — This is a large thick muscle divided at its 

 origin into two parts, superior and inferior. The superior, the 

 larger, arises from the crest and posterior surface of the ilium. 

 The anterior has a narrow origin, from the same surface, close to 

 the cotyloid border of the bone. The two portions are united 

 below, at their insertion into the great tuberosity of the femur. 

 The superior part is supplied by a branch from the sacral plexus. 

 The anterior part is supplied by a branch which arises in abdomen 

 from the anterior crural, and, passing under the rectus, is dis- 

 tributed to this portion of the muscle. Meckel and Mivart in 

 Echidna describe this as minimus. From the nerve-supply it 

 would seem that only posterior portion corresponds to ordinary 

 gluteus medius. The anterior portion may be a muscle divorced 

 from the muscles in front of the thigh. There is a small muscle 



1 Mivart. 



