390 MR. ST. GEORGE MIVART ON THE VERTEBRATE SKELETON. 
Thus at present, I think, we are hardly in a position to generalize the expression of 
the vertebrate limb more than to take it, in our typical form, as a pentadactyle member 
differentiated as in vertebrates generally, and approximating to what we find in certain 
amphibians. 
Of course, we may be confident à priori that the typical differentiation of the higher : 
classes has been evolved from some antecedent quasi-piscine condition. But that con- 
dition does not seem to me yet to have been made out; and, whatever may be in future 
determined by further investigations into known forms, or by the discovery of others as 
yet unknown, I hardly think that the view propounded by Professor Gegenbaur is the 
one destined eventually to prevail. 
Summing up what has been stated, then, the divisions of the vertebrate skeleton may, 
according to the views here advocated, be conveniently represented as follows :— 
[ AU AI uL LO { en 
: ( Epaxial 
(neural arches 
and spines). 
( Superior 
(diapophyses 
and ribs 
Skeleton .... wi dar Paraxial ....< Inferior 
pem np « (parapophyses, 
ribs, and ster- 
( num). 
Endoskeleton 4 
Superior 
Hypaxial (hypapophyses). 
Inferior 
L \ Appendicular. (visceral arches). 
The most generalized and simplest expression of observed facts may also, I think, be 
_ diagrammatically represented as it is in Plate LIII. fig. 1. 
I will conclude in the words of Professor Jeffries Wyman* :—* Such a conception as 
an archetype involves is necessary in our attempts to study the creative idea which un- 
derlies all animal structures, apart from their adaptation to the modes of existence in 
each species; and just in proportion as such conception is based upon a more and more 
complete knowledge of the plan of structure and of development, anatomy will, in the 
same degree, become philosophical.” 
* “On Symmetry and Homology in Limbs,” Proceedings of the Boston Society of Natural History, vol. xi. June 
5th, 1867. 
