EEPORT ON THE SPHENISCID^. 97 



Attachments. — According to Schoepss, this muscle in Splieniscus de'mersus is repre- 

 sented by a slender tendon, whicli arises from the lower part of the inner surface of the 

 ulna, and after coursing along the inner side of the radial metacarpal bone, is inserted into 

 the inner side of the base of the first radial phalanx. 



Remarhs. — I failed to find any trace of a tendon answering to this description in 

 Spheniscus dpnersus, or in any other species which I examined ; neither is it referred to 

 by Gervais and Alix in their account of the myology of Eudyptes chrysolopAus. 



(f) Muscles inserted into the Phalanges. 

 1. Extensor indicis prop)rius. 



L'extensevr externe du doigt (?), Vicq d'Azyr, 1773, p. 574, No. 3. 



Der Streclcer der ersten imd zioeitev Gliedes des zweiten Fingers, Tiedemann, p. 323, No. 5. 



Der dussrre, oder hint ere Strecker des ersten und zweiten Gliedes des zweiten Fingers, Heusinger, 



p. 193, No. 35. 

 L'extenseur propre du deuxihme doigt, Meckel, vol. vi. p. 69, No. 2. 

 Fxtensor indicis j)ropritis longus, Schoeps.s, p. 159, No. 38. 



Extensor digiti indicis proprius loiigus et hrevis, Selenka, vol. vi. p. 132, No. 62. 

 Extenseur de la deuxieme phalange du doigt imdian, Gervais and Alix, p. 28. 



Attachments. — This is a very slender muscle. It arises from the contiguous borders 

 of the radius and ulna, below the origin of the extensor metacarpi radialis brevis, and 

 terminates on a delicate tendon, which, after passing over the wrist joint and along the 

 outer surface of the radial metacarpal bone, is inserted into the outer side of the second or 

 terminal radial phalanx. 



Action. — It extends the hand at the wrist joint. 



Relations. — The muscle is deeply situated between the lower ends of the radius and 

 ulna, and is concealed by the tendon of the extensor communis digitorum. 



Nerve supply. — A twig from the interosseous branch of the musculo-spiral nerve. 



Variations. — In one specimen of Aptenodytes longirostris this muscle was absent, and 

 its insertion replaced by a supernumerary tendinous slip derived from the extensor com- 

 munis digitorum. 



Rema)-ks. — According to Meckel, this muscle in the Penguin is represented entirely 

 by tendon. Schoepss found that its origin was confined to the lower end of the radius. 

 The muscle is apparently described by Reid, but his description is unsatisfactory. 



2. Extensor communis digitorum. 



Le flechisseur de Vappendix, Vicq d'Azyr, 1773, p. 574, No. 4. 



Uabdudeur commun, Cuvier, vol. i. p. 526. 



Der g/'osse Damnenanleger, Merrem, p. 157, No 10. 



(ZOOL. CHALT. FXP. PART XVIII. 1883.) S 13 



