238 TRANSACTIONS OF THE [may. 13, 
The combination of gleno-radial and gleno-uluar muscle is also 
noted in the Pig and Cat. 
VII. Gleno-radial and Coraco-ulnar. 
Uromastix spinipes.* 
Origin: by two distinct portions from coracoid, one tendin- 
ons from proximal part, the other muscular more laterally from 
anterior part, corresponding with the coracoid and glenoid 
origins in man. 
Insertion: After being joined by Brachialis anticus, which 
is large, arising from the lower part of the humerus, the con- 
joined tendon is inserted into the radius and ulna. 
VIII. Coraco-radial and Gleno-ulnar. 
In Marsupials, in which the two muscles are entirely separate 
from each other.+ 
IX. Coraco-Radial and Coraco- Ulnar. 
This arrangement of the muscle is found in Emys and Cha- 
meleon.}{ 
A general consideration of the facts above adduced leads to 
the natural conclusion that the Biceps muscle of the fore-limb, or 
its homologue, presents throughout the vertebrate series evi- 
dences in its structure and arrangement of a general type-plan 
of construction, modified in the different groups by the functional 
requirements of the jimb, and in all probability by the varying 
relations assumed by the tendon of origin to the capsule and 
the cavity of the humero-scapular articulation. I believe that 
this fundamental type-construction of the appendicular muscular 
system is the element to which we must refer forthe explanation 
of deviations from the arrangement normally found in any one 
species. Partial returns to the potential type-form constitute 
reversions of far broader significance than those usually grouped 
under the head of atavism. 
In respect to the human subject, as well as in the case of the 
remaining vertebrates, and especially mammalia, our exact 
knowledge regarding the lines of descent of present orders and 
sub-orders is still so rudimentary and imperfect, that the im- 
propriety of referring nearly all muscular variations to atavism 
and direct inheritance becomes at once apparent. The fact that 
*Humphry, op. cit., p. 64. 
+Krause, op. cit., p. 223. 
tKrause, op. cit., p. 223. 
