REPORT ON THE SPHENISCIDxE. 101 



Action. — This muscle extends the first and second radial phalanges upon the meta- 

 carpal bone, and upon one another. 



Relations. — ^It rests on the dorsal surface of the metacarpal bones, and is covered by 

 the alar aponeurosis. 



Nerve szipply (?) 



Variations. — In one specimen of Aptenodytes longirostris, as well as in Spheniscus 

 minor, this muscle was entirely absent ; while in a specimen of Eudyptes chrysocome 

 from Kerguelen, as also in one of Pygosceles tceniatus, the muscle was represented by 

 a tendon without muscular belly. In other specimens of both these sjiecies the muscle 

 was arranged as above described. 



Remarks. — According to Schoepss, this muscle is entirely absent in Spheniscus 

 demersus. Gervais and Alix found it in Endyptes chrysolop>hus, in which bird it pre- 

 sented the disposition above described. The observations of these authors with regard 

 to its presence in Eudyptes chrysolophus agree with my own. 



8. Interosseus palmaris. 



Der innere Mittelliandmuskel, Tiedemann, p. 825, No. 11. 

 Der innere MitfelhandmusTcel, Heiisinger, p. 197, No. 40. 

 L'extenseur et ahdudeur externe, Meckel, vol. vi. p. 77, No. 7. 

 Der Beuger des Zeigefingers, Schoepss, p. 173, No. 47. 

 Intei-osseus, Selenka, vol. vi. p. 137, No. 69. 

 Interosseux palmaire, Gervais and Alix, p. 30. 



Attachments. — The interosseous palmar muscle like the dorsal is very slender. 

 It arises from the contiguous borders of the radial and ulnar metacarpal bones. Its 

 tendon passes along the palmar surface of the wing lying between the first radial and 

 ulnar phalanges, and is inserted into the inner side of the base of the last radial phalanx. 



Action. — This muscle flexes the first and second radial phalanges upon the meta- 

 carpal bone, and upon one another. 



Relations. — It rests on the palmar surface of the metacarpal bones, and is concealed 

 by the long flexor tendons of the fingers, as well as by the alar aponeurosis. 



Nerve supply (?) 



Variations. — In one specimen of Pygosceles tceniatus, as well as in Spheniscus minor, 

 this muscle was absent. 



Remarks. — The description of Gervais and Alix of this muscle in Eudyptes cliryso- 

 loplius agrees with the above. According to Schoepss, in Spheniscus demersus the muscle 

 is inserted not into the base but into the distal extremity of the second radial phalanx. 



Comparative Remarks. 

 Having now described the muscles of the wing, and the varieties which these present 



