416 THE NATURAL HISTORY REVIEW. 



As some time has now elapsed, and I have seen no reason to 

 make any change in my views, I venture to bring the subject again 

 before the public. 



The fossil bird, as is well known, is preserved on two slabs of the 

 Solenhofen lithographic stone. One of these, containing the principal 

 bones and the clearest impressions of the feathers, I shall speak of 

 as the principal slab ; and the other, which though containing but few 

 of the bones, is still of the utmost importance for completing our 

 knowledge of the character of the fossil, I shall term the counterpart. 



On the principal slab, between the posterior margin of the right 

 wings and the lower extremity of the right tihia of the bird, is a 

 rounded protuberance, in general outline forming a crescent, with a 

 depression in the centre of its convex side, dividing it into two lobes. 

 On the concave side of the crescent, the limestone of the slab rises 

 to a higher level than it does on the convex side, so that the outline 

 of the lobes is not so well defined on that side, and the upper portion 

 of one of them has moreover been broken off together with a portion 

 of the matrix. Around the margin of the crescent-shaped pro- 

 tuberance may be discerned a section of a thin film of sparry 

 matter, representing the place where bone has been, which is con- 

 tinued on in a curved line beyond the outer end of the more perfect 

 lobe, forming as it were a long thin horn of the crescent. 



The counterpart does not exactly correspond with the principal 

 slab, as a portion of the matrix has been chipped away from the 

 latter since the block was split, causing the injury to one of the lobes, 

 which I have already mentioned ; but in it, is a crescent-shaped portion 

 of the sparry layer which takes the place of bone in the slab, show- 

 ing the two concavities in which the rounded lobes on the principal 

 slab were moulded, with a projecting ridge between them. 



There can, I think, be but little hesitation in recognizing in this 

 crescent-shaped object, a portion of the anterior part of the missing 

 cranium of the Archseopteryx, while on the slab itself is a cast of a 

 portion of the brain-cavity, showing distinctly the two hemispheres 

 of the brain and the median line, corresponding with the intercerebral 

 ridge, which is so plainly visible on the counterpart. 



Indeed, so evidently is this the case, that Mr. Carter Blake 

 recognises upon the cast of the brain " the site of the olfactory 

 lobes,"* and perhaps " some trace of the optic lobe beneath the 

 brain." 



* Geologist, Vol. vi. p. 7. 



