274 report— 1846. 



All those bones which represent single vertebral elements are ' teleologi- 

 cally compound,' when developed from more than one centre, whether such 

 centres subsequently coalesce, or remain distinct, or even become the subject 

 of individual adaptive modifications, with special joints, muscles, &c. for par- 

 ticular offices. 



In the human skeleton, the clavicles, the (thoracic vertebral) ribs, are in- 

 stances of simple and truly individual bones. The occiput, sphenoid, eth- 

 moid, temporal, superior maxilla, mandible, hyoid, scapula, the so-called true 

 vertebrae, the sacrum and coccyx, the sternum, and ossa innominata are 

 * homologically ' compound bones. 



The two parietals are essentially like the frontal and vomer, one 'teleologi- 

 cally ' compound bone : so, likewise, are the two nasals. And, if the view of 

 the homology of the jointed filamentary skeleton of the rudimental ventral 

 fin of the lepidosiren with the simple diverging appendages of the costal 

 arches of the abdominal vertebra? be correct, then is not merely the mam- 

 malian femur a teleologically compound bone, but the whole skeleton of the 

 hind-limb from the femur to the distal phalanges inclusive must be regarded 

 as representing the essentially single vertebral element, here called 'diverging 

 appendage,' subdivided according to the law of vegetative repetition of centres; 

 which law is progressively overruled and masked by the supervention of the 

 higher law of special modification and adaptation of such vegetative subdivi- 

 sions to the exigences and habits and sphere of life of the species. 



In many animals all the parts of the skeleton of the limbs, and in all ani- 

 mals some of the parts, are simple bones, in the sense of being developed 

 from a single centre ; but in none can they claim that essentially individual 

 character which the clavicles and osseous parts of the ribs are entitled to, as 

 being primary vertebral elements. 



To trace the mode and kind and extent of modification of the same ele- 

 mentary parts of the typical segment throughout a large natural series of 

 highly organized animals, like the vertebrata ; and to be thus led to appreciate 

 how, without complete departure from the fundamental type, the species are 

 adapted to their different offices in creation, brings us, as it were, into the 

 secret counsels that have directed the organizing forces, and is one of the 

 legitimate courses of inquiry by which we may be permitted to gain an in- 

 sight into the law which has governed the successive introduction of specific 

 forms of living beings into this planet. 



Vertebra; of the Skull. — Since it has been found that the bones of the trunk 

 maintain through every kind and degree of adaptive modification, whether as 

 ' thorax,' ' carapace ' or ' sacrum,' an arrangement into segments in the con- 

 stitution and relative position of the parts of which the vertebral type has been 

 universally recognised — let us next examine, without bias, and, if possible, 

 without reference to or recollection of previous attempts, in the first instance, 

 whether such type be traceable through the remaining anterior part of the 

 axis of the endo-skeleton, which, like the thorax and pelvis, has received, on 

 account of its degree of coalescence and other modifications, the special col- 

 lective term of ' skull ;' — or, whether nature has, in this part of the endo-ske- 

 leton, so far departed from the pattern on which all the rest is constructed, 

 that we cannot, without manifest violence to her arrangements, demonstrate 

 the segmental composition ; or refer, without admitting modifications distinct 

 in kind as well as degree from those that mark the vertebral character in the 

 trunk, the constitution of such segments to the vertebral type. 



Taking the conical skull of an ordinary osseous fish — that of the cod (Mor- 

 rhtta vulgaris) for example, — if we detach the bones which form its hinder 

 extremity, or base, and which immediately precede and join the atla?, from 



