92 INTRODUCTION. 



out a trace. The body of the hyoid cartilage of the 

 transformed animal is composed of the two united 

 branchial plates, the posterior copula, and of newly 

 formed cartilage, constituting the manubria of the 

 principal cornua, probably derived from the copula. 



The alar and postero-lateral processes are new 

 formations which only appear comparatively late. 

 The so-called "processus thyroidei" [thyrohyals, Q 

 have nothing to do with the branchial processes (nor 

 with the ceratobranchials of Parker, which Gaupp 

 terms spiculci), but are remains of the posterior portion 

 of the larval branchial plates. 



Thus, of the larval apparatus nothing is preserved 

 but the hyal arch, and a portion of the copula and of 

 the two branchial plates. 



Dr. W. G. Ridewood has recently investigated the 

 development of the hyobranchial skeleton of Pelodytes, 

 and the careful figures he has drawn are reproduced 

 here with his kind permissiou. He agrees with Gaupp 

 in the main results, but shows the postero-lateral 

 process to be the persistent proximal portion of the 

 first ceratobranchial. 



In Pelodytes as well as in Pelobates the anterior 

 processes are expanded and bent inwards, and the 

 cornua become broken, the anterior portion fusing 

 with the alar processes, whilst the posterior becomes 

 free from the hyoid plate, as may be seen on Fig. 38. 



In order to complete this rapid sketch of the 

 evolution of the hyobranchial apparatus, which is of 

 great importance for the correct understanding of the 

 hyoid apparatus in the perfect form, it remains to 

 notice that in the Dlscoglossldx the first copula or 

 basihyal is of much larger size than in other frogs, 

 and persists longer ; whilst the second extends farther 

 back, and completely separates the hyobranchial 

 plates from each other. 



The ossification of the thyroid processes takes place 

 only after transformation. 



The only cranial ossifications to develop during the 



