216 Zoological Society. 



origin from scattered tendinous threads in the subcutaneous cellular 

 tissue of the abdomen : it passes upwards, outwards and forwards, 

 and is inserted fleshy into the proximal part of the humerus, which 

 it seems to depress*. 



Muscles of the Trcxk. 

 A. On the Dorsal Aspect. 



The muscles on the dorsal aspect of the vertebral column in Birds 

 have only of late years received any attention from Com])arative 

 Anatomists : they have been mentioned rather than described by 

 Tiedemann and Meckel : Cams has given a side-view of the super- 

 ficial layer of muscles in the Sparrow-hawk ; tbeir best description 

 is contained in the second edition of the ' Lecons d'Anatomie Com- 

 paree ' of Cuvier. 



The muscles of the back are in general so feebly developed in 

 birds of flight, that they were affirmed by Cuvier to be wanting 

 altogether in the first edition of the ' Lemons.' And this is almost 

 true as respects their carneous portion, for they are chiefly tendinous 

 in Birds of Flight. In the Struthious birds, and in the Penguin, 

 in which the dorsal vertebrae are unfettered in their movements by 

 anchylosis, these muscles are more fleshy and conspicuous ; but they 

 attain their greatest relative size and distinctness in the Apteryx. 



From the very small size of the muscles which pass from the 

 spine to the scapula and humerus in the Apteryx, the true muscles of 

 the back, which correspond to the second layer of the dorsal muscles 

 in Man, become immediately visible on removing the dorsal integu- 

 ments and fasciae ; they consist of the sacro-lumbalis, longissimus 

 dor si, and spinalis dorsi. The first two muscles are blended toge- 

 ther at their posterior origins, but soon assume the disposition cha- 

 racteristic of each, as they advance forwards. 



The sacro-lumbalis is a strong and fleshy muscle, six lines in 

 breadth, and three or four lines in thickness : it is, as usual, the most 

 external or lateral of the muscles of the back, and extends from the 

 anterior border of the ilium to the penultimate cervical vertebra. 

 Origin. By short tendinous and carneous fibres from the outer half 

 of the anterior margin of the ilium, and by a succession of long, 

 strong, and flattened tendons from the angles of the fifth and fourth 

 ribs, and from the extremities of the transverse processes of the 

 third, second, and first dorsal vertebrae ; also by a shorter tendon 

 from the transverse process of the last cervical vertebra ; these 



* In Mammalia the cutaneous muscles form a more continuous stratum 

 than ill the Apteryx and other bii-ds, and hence have been grouped together 

 under the conunun term paiuiiculus carno.sus; they have also, in general, 

 both their origins and insertions in the integument ; but in Birds, in 

 which the integument supports so extraordinary an abundance of the epi- 

 dermic material under the form of feathers, the muscles destined to its 

 especial motions require a more fixed attachment from whicli to act. The 

 Rhinoceros, in which the integuments, from the thickness and density of its 

 coriiim, is in a similar condition as regards the resistance to be o%-ercome 

 by the skin-muscles, presents an analogous condition of its panniculus car- 

 nosus, having it divided into several distinct muscles, most of which take 

 their origin from bone or fascia? attached to bone. 



