314 Dr. A. Macalister on the Formation of 
regarding the two limbs not immediately as being representa- 
tives the one of the other, but as different expressions of a 
certain type limb, to some extent ideal because not found as 
an unmodified entity in any animal, but upon whose basis 
every vertebrate limb is constructed; and apprehending this, 
we should compare the individual limb before us with the cor- 
responding’ part of the type extremity,—just as in the science 
of botany we learn that the various parts of the flower (sepal, 
petal, stamen, and carpel) are modifications, not of the leaf as 
Goethe taught, but of a certain ideal.organism or phyton, of 
which the leaf itself is only a variety. 
As the study of comparative osteology leads us to the con- 
clusion that there is a typical skeleton, of which all vertebrate 
skeletons are modifications, so the study of myology teaches 
us that there is a typical vertebrate myozoon*, of which the 
individual vertebrate muscular systems are modifications. 
Adopting the theory of a myozoon, the main point of our 
inquiry resolves itself into a determination of the nature and 
components of the typical limb; and in our researches we 
shall commence with such portions as present us with the 
most clear and constant uniformities of arrangement, and con- 
sequently with the fewest difficulties. Thus we will, in the 
first place, endeavour to resolve into their typical positions the 
muscles of the terminal segment of the vertebrate limb—the 
pes or the manus. oe 
There is no primary difficulty in deciding the landmarks in 
this segment: the we and hallux, the little toe and little 
finger, the carpus and tarsus are undoubtedly correspondent ; 
and. the latter may be arranged as follows into a tabular series 
whose resemblances are evident :— | 
Scaphoid = os naviculare pedis. 
Semilunar = astragalus (body). 
Cuneiform. = calcaneum. 
Pisiform | = sesamoid bone in the long peroneal tendon. 
Trapezium = entocuneiform. 
Trapezoid = mesocuneiform. 
Os magnum : 
(body) = ectocuneiform. 
(head) = astragalus (head). 
Unciform. = cuboid. 
Of the five digits typically present there are two which ge- 
* I should, perhaps, apologize for attempting to intrude a new name 
upon an te n6c fe name-encumbered science ; but I think any new word 
may be admitted whose meaning is easily understood, when it saves us 
the trouble of cireumlocution. Myozoon = uis (éov, muscle animal. 
