78 THE VOYAGE OF H.M.S. CHALLENGER. 



Relations. — The muscle is subcutaneous. It interdigitates witli the external 

 oblique of the abdomen, and rests against the ribs. 



Nerve supply. — A branch from the great cord of the brachial plexus. This branch 

 comes off from the brachial plexus above the origin of the branch to the pectoralis major, 

 and divides into two twigs. One of these supplies the serratus anticus major, and the 

 other the serratus anticus minor. 



Variations. — In Pygosceles tceniatus this muscle arises by means of two digitations 

 from the outer surfaces of the fourth and fifth ribs only. In this respect Pygosceles 

 difiers from every other species which I have examined. 



Remarks. — According to Schoepss and Selenka, this muscle in the Penguin arises from 

 four ribs. Such is not the case in any species of Penguin examined by myself. 



4. Serratus anticus minor. 



Costo-scapulaire, Vicq dAzyr, 1772, p. 629, No. 4. 



Codo-scapulairr, Cuvier, vol. i. p. 262. 



Der untere RippcmchuUerblattmnskel, Wiedemann, p. 87. 



Costo-sca]mlaris, Tiedemann, p. 304, No. 6. 



Petit pectoral on petit dentelr anti'neur, Meckel, vol. vi. p. 25, No. 7. 



Der Ideine vordere SdgemuskeJ, Schoepss, p. 96, No. 9. 



Serratus anticus (part of), Selenka, vol. vi. p. 110, No. 35. 



Grand dentele anterieur, Gervai.s and Ali.x, p. 20. 



Attachments. — This muscle arises by means of three digitations from the outer surfaces 

 of the second, third, and fourth vertebral ribs, immediately below their costal processes. 

 The fibres pass obliquely forwards and upwards, and are inserted into the anterior third 

 of the outer or axillary border of the scapula. 



Action. — The muscle pulls the scapula backwards and downwards, or, taking the 

 scapula as its fixed point, it elevates the ribs from which it arises. 



Relations. — The muscle is overlapped superficially by the external border of the 

 infra-spinatus. In contact with its low^er border are the axillary vessels and nerves, as 

 they pass from the chest. At its origin it interdigitates ■ndth the external oblique 

 of the abdomen. Its insertion separates the origin of the subscapularis from that of 

 the supra-spiuatus. 



Nerve suiop)ly. — A branch from the great cord of the brachial plexus. This branch, 

 after supplying a twig to, and perforating the serratus anticus minor, terminates in the 

 serratus anticus major. 



Variations. — In Eudyp>tes chrysocome from the Falkland Islands, as well as in a speci- 

 men of the same species from Kerguelen, the origin of the serratus minor was limited to 

 the third and fourth ribs. This was also the case in Eudyptes chrysolop)hus, and in 

 Spheniscus mendicnlus. In Spheniscus demersus the muscle arose by a single digitation 



