1876.] 



Structure of the Skull in Urodelous Amphibia. 



333 



II. ^''On the Structure and Development of the Skull in the 

 Urodelous Amphibia. ''—Part I. By W. K. Parker, F.R.S. 

 Received November 9, 1876. 



(Abstract.) 



Through the kindness o£ several friends * I have been enabled to work 

 out the development of the skull in a Salamandrian type, which can now 

 be compared with that of a Batrachian. 



I was the more anxious to do this work perfectly (it had been done in 

 part) because Professor Huxley showed me, some two years ago, certain 

 errors in my first paper on the Batrachian skull; and I \;\dshed not 

 only to go over that ground again, but also to have the morphology of 

 the Salamandrian type of skull quite mastered, so that the two might be 

 compared together. 



Moreover one important error in my first paper (on the Frog's skull) 

 arose from my taking it for granted that a certain element, the " stapes," 

 arose similarly in the two groups. Also an impetus was given to me by 

 the publication of Professor Huxley's article on the " Amphibia " in the 

 ninth volume of the ' Encyclopaedia Britannica,' and his invaluable paper 

 on the skull of Menohranchus (a low Perennibranchiate Urodele) in the 

 * Proceedings of the Zoological Society ' (January 1874). 



In the present paper I have shown the condition of the skull in nine 

 stages of the Axolotl (Siredon) ; and then, as a tenth stage, the skull of 

 Amhlystoma is given, the Salamandrian into which certain individual 

 Axolotls pass when they take on a higher metamorphic condition. 



But the earlier stages of the cranium of Sireclon are well illustrated by 

 what is seen in the lower Perennibranchs. Prof. Huxley's interesting 

 Menohranchus is not nearly so low and simple a type as that here given 

 by me, namely Proteus. 



Moreover the truly Salamandrian Amhlystoma is not an average kind 

 of " Caducibranch," but differs from the majority of the species in several 

 particulars. Serlonata persjpicillata, one of the smallest of the order, is a 

 good average type ; and happily a little larva of this species gives me an 

 intercalary stage between my third a,udfou7'th of Siredon. 



The materials here offered to the Eoyal Society are but a portion of 

 what I could have offered ; but as the bulk of such a communication would 

 have been far greater than I can ask space for, I have here and there 

 made reference to unpublished matter on the skull of a number of these 

 tailed Amphibians. 



After describing these skulls in then' stages, and through their changes, 

 I have made a somewhat detailed comparison of the Salamandrian with 

 the Batrachian type of skull. 



* Messrs. Gllnther, Flower, Murie, Mivart, A. Agassiz, Rupert Jones, and Teget- 

 meier, especially the last named. 



