Mr. W. K. Parker on the Skull of the Common Fowl. 69 



become struthious ; and now parosteal tracts (the angular, suvan- 

 gular, deutary, &c.) appear round the mandibular rod. 



In this abstract I shall not trace the changes of the skull any 

 further, but conclude with a few remarks on the nomenclature of 

 certain splints, and as to the nature of the great basicranial bones. 



Some years ago I found that certain birds (for instance the Emeu) 

 possessed an additional maxillary bone on each side ; knowing that 

 the so-called "turbinal" of the Lizard and 8nake was one of the 

 maxillary series I set myself to find the homologies of these splints. 

 Renaming the reptilian bones " praevomers," on account of their 

 relation to the vomer, and supposing the feeble maxillaries of the 

 Bird to represent them, I considered that the true maxillaries were 

 to be found in those newly found cheek-bones of the Emeu and 

 some other birds. 



After discussion with Professor Huxley I have determined to drop 

 the term " prBevomer," and to call the supposed turbinal of the 

 Lizard "septo-maxillary," and the additional bone in the Bird's face 

 " postmaxillary." 



In many Birds, but not in the Fowl, the " septo-maxillary " is 

 largely represented — not, however, as a distinct osseous piece, but as 

 an outgrowth of the true maxillary. 



With regard to the basicranial bones, I have now satisfied myself 

 that the " parasphenoid " of the Osseous Fish and the Batrachian 

 reappears in the Bird as three osseous centres — all true " parostoses," 

 as in the single piece of the lower types ; these three pieces are, the 

 "rostrum" of the basisphenoid and the two " basitemporals." 



These three centres rapidly coalesce to form one piece, the exact 

 counterpart of the Ichthyic and Batrachian bone ; but just as this 

 coalescence begins, ossification proceeds inwards from these " paros- 

 toses," and affects the overlying cartilage, the cartilage of the basi- 

 sphenoidal region having no other osseous nuclei. This process of 

 the extension inwards of ossification from a splint-bone to a cartila- 

 ginous rod or plate I have already called " osseous grafting " *. 



In my former paper the basisphenoidal " rostrum " and " basi- 

 temporals" were classed with the endoskeletal bones ; they will in 

 the present paper be placed in the parosteal category, in accordance 

 with their primordial condition. 



By the careful following out of these and numerous other details 

 I have corrected and added to my previous knowledge of the early 

 morphological conditions of the Bird's cranium, and at the same 

 time, I trust, have contributed to an enlarged and more accurate 

 conception of the history and meaning of the Vertebrate skull in 

 general. 



March 18, 1869.— Dr. William Allen Miller, Treasurer and Vice- 

 President, in the Chair. 



" On the Structure of the Red Blood-corpuscle of Oviparous Ver- 

 tebrata." By William S. Savory, F.R.S. 



The red blood-cell has been perhaps more frc(juently and fully 

 examined than any other animal structure ; certainly none has 



* See memoir " Ou the Sliouldcr-girdlc and Sternum," Ilay Soc. 18G3, p. 10. 



