22 
February 22, 1842. 
William Horton Lloyd, Esq., in the Chair. 
The reading of the Second Part* of Prof. Owen’s Monograph on 
the Apteryx australis, Shaw, including its Myology, was completed. 
The following is the descriptive portion of this communication : — 
Muscuzs or THE SKIN. 
No detailed description of the muscles of the skin in Birds has 
been given either in the systematic works on comparative anatomy, 
or in particular treatises ; these muscles appear indeed in general to 
be too irregularly or too feebly developed to have attracted much 
attention ; brief notices are recorded of some peculiarly developed 
cutaneous muscles, as those which spread the plumes of the peacock, 
and erect the hackles of the cock; the compressors of the subcuta- 
neous air-cells are noticed in the anatomical account of the Gannett 
(Sula Bassana}), and a more constant cutaneous muscle, viz. that 
which supports the crop in gallinaceous birds, is briefly mentioned 
and figured by Hunter f. 
In the Apteryz, the subject of the present Myography, the cuta- 
neous system of muscles presents a more distinct and extensive 
development than has hitherto been met with in the class of Birds— 
a condition which is evidently connected with the peculiar thickness 
of the integument, and probably with the burrowing habits of the 
“present species, which possesses in this structure the power of 
shaking off the loose earth from its plumage, while busy in the act 
of excavating its chamber of retreat and nidification. 
Constrictor collimThe whole of the neck is surrounded by a thin 
stratum of muscular fibres, directed for the most part transversely, 
and extending from an attachment along the median line of the skin 
at the back of the neck, to a parallel raphé on the median line of the 
opposite side: this muscle is strongest at its commencement or 
anterior part, where the fibres take their origin in a broad fasciculus 
from the outer part of the occipital ridge ; these run obliquely down- 
wards and forwards on each side of the neck, but are continued 
uninterruptedly with those arising from the dorsal line of the skin 
above mentioned; the direction of the fibres insensibly changing 
from the oblique to the transverse. The outer surface of this 
muscle is attached to the integument by a thin and dense layer of 
* See Transactions of the Zoological Society, vol. ii. part 4. p. 257, 
Splanchnology and Osteology. 
+ Proceedings of Zoological Society, 1832, p. 91. 
t In description of pl. 10, vol. i. of Physiological Catalogue of Hunterian 
Collection, by Owen, 4to. 1833-1841. 
