360 Dr Barry on the Unity of' Structure 



the nerves connected with the latter, may be illustrated in the 

 same manner ; they seem, as it were, rude copies of each other, 

 differing only in direction and degree. 



Secondly, Let the point A be considered as the common ori- 

 gin, in the fleshy portion of the lamina dorsalis and ventralis, of 

 a series of osseous arcs, which, taking those of both sides, form 

 an outer tube, including the upper and the under tube. 



Fig. 8. 



Ideal Transverse Section of a Vertebrated Animal, to shew the Type of the 



Extremities. 



a Stem of the vertebral column. 



b Arches of the Vertebrae. 



c Ribs. 



d Dorsal 1 



e Ventral J radlcal P ortlon ' 



/ Upper 1 . - }> of an Extremity, &c. 



g Under { middle P OItlOD - 



h Terminal portion. 



h' Terminal portion as a Fin. 



(This fig. is taken from Von Ear.*) 



The curves may now illustrate the development of the radi- 

 cal portion of either an extremity, viz. of the scapula and cla- 

 vicle, on the one hand, and of the outer portion of the os inno- 

 minatum,-)- on the other, or that part of the base of the cranium, 

 which, formed by ~ne of those osseous arcs, and having coa- 

 lesced with the cranial vertebrae, serves to articulate the upper 



* This figure also, was exhibited in our last paper. Its re-appearance is 

 needful for the reason before given regarding Fig. 1 1. 



+ The inner portion of this bone being probably, as Von Bar supposes, 

 analogous to ribs, derived from the under tube, and coalescing with a section 

 of the outer, to constitute the pelvis. 



t Von Bar. 



