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 

 eveiy vertebrate limb is consti-ucted ; 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 

 inquiiy 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. 



There is no primary difficulty in deciding the landmarks in 

 this segment : the pollex 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. 



Pisiforai = 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 already name-encumbered science ; but I think any new word 

 may be admitted whose meaning is easily understood, when it saves us 

 the trouble of circumlocution. Myozoon = uvs Caov, muscle animal. 



