REPORT ON THE SPHENISCID.5:. 53 



MUSCLES OF THE TEUNK.i 



(a) Cutaneous Muscles. 



1. Dorsal cutaneous muscle. 



Dermo-spinalis, Owen, p. 24. 



Panniculus carnosus (second portion) EeiJ, p. 139. 



Tenseur de la membrane axillaire, Gervais and Alix, p. 38. 



Attachments.— This, muscle is quadrilateral in form. It arises from the posterior half 

 of the spinous process of the fourth, from the spinous jKocess of the fifth, and from that 

 of the sixth dorsal vertebra. The fibres pass transversely outwards, and are inserted 

 into the subcutaneous fascia of the lateral fine of the trunk. 



Action. — It pulls the integument of the flank towards the spine. 



Relations. — The muscle is subcutaneous, and rests upon the trapezius and latissimus 

 dorsi. 



Nerve supi^ly. — Several branches from the posterior divisions of the dorsal spinal 

 nerves. 



Variations. — In Aptenodytes longirostris the muscle is better developed than in any 

 other species. In it the anterior fibres end in a delicate aponeurosis, which covers the 

 shoulder joint, while the posterior fibres terminate in the subcutaneous fascia covering 

 the knee. 



In Splieniscus inagellanicus, as well as in Spheniscus minor, the muscle is relatively 

 smaller than in Eudyptes chrysocome, and arises only from tivo dorsal spines. 



In both specimens of Pygosceles tceniatus which I dissected, this muscle was entirely 

 wanting. 



Remarks. — As observed by Gervais and Alix, the costal fasciculus of this muscle, which 

 is present in the majority of bii-ds, is entirely absent in every species of Penguin. 

 According to these authors, in Eudyptes clirysolophus the muscle presents the arrange- 

 ment above described in Aptenodytes. In the specimens of Eudyptes chrysolophus 

 examined by myself, the muscle was scarcely so well developed as in A^itenodytes, and 

 presented the arrangement described above in Eudyptes chrysocome. 



2. Constrictor colli. 



Z)e?' Hautmuskel des Raises, Tiedemann, vol. i. p. 133. 

 Paimiculiis carnosus (part of), Reid. p. 139. 

 Constrictor colli, Owen, p. 22. 

 Peaucier du cou (plan superficiel) Gervais and Alix, p. 39. 



Attachments. — This, the more superficial of the two cutaneous muscles of the neck, con- 

 sists of a number of circularly arranged muscular fibres which lie immediately underneath 



' In describing the muscles it will be understood that I imagine the trunk of the bird to be horizontal, with the 

 vertebral column directed upwards. 



