The Columella Aiiris in Ampliibia. 613 



the Urodela the condition is less satisfactory. Parker, Wiedersheim 

 and Stohr had emphatically declared the origin of the operculum 

 from the ear capsule and the absence of any association in develop- 

 ment with the hyoid arch. 



More recently in a paper before the Anatomische Gesellschaft 

 Tuchs ('07) rejected completely the hyomandibular homology^^ 

 of the amphibian structures, basing his conclusions upon the otic 

 origin of the operculum in Salamandra (See p. 568). The presence 

 of a stilus was regarded by him as secondary, the operculum without 

 stilus representing the primitive condition. In the discussion, the 

 homology with the hyomandibulare was upheld by several. Gaupp 

 at that time ('07, pp. 31 and 32) stated his conception of the primi- 

 tive "Columella auris" as consisting of an operculum and a stilus, 

 the latter articulated with the palatoquadrate. Since the hyoman- 

 dibulare in fishes is, in many forms, between the palatoquadrate and 

 the otic capsule, the connection of the stilus with the palatoquadrate 

 strongly suggests the homology. He admitted the lack of ontogenetic 

 evidence, but pointed out the difficulty attending the delimitation 

 of what might be hyal blastema from the periotic blastema. Since' 

 the upper end of the hyoid arch closely adjoined the otic capsule, 

 blastema of the hyoid arch, it is easily conceivable, might be early 

 incorporated with the periotic, and the operculum might develop 

 apparently as part of the ear capsule and nevertheless be of hyoid 

 origin. In his rejoinder Fuchs (pp. 33, 34) affirmed his belief that 

 the operculum without stilus was the more primitive ; that the f enes- 

 /tra arose as a result of the action of a "biological factor" Avithin 

 Ithe ear itself upon the assumption of terrestrial life ; that the "rvib- 

 jbing" of the hyomandibulare could in no wise have caused the 

 (appearance of the fenestra vestibuli, since in the numerous fish forms 



'•'Fucbs ('07, p. 24) : "Ich eraclite clas Operculum bezw. Operculum + 

 Stilus der Urodelen fur homolog dem Otostapes der Reptilien und beide fiir 

 bomolog dem Stapes der Saugetiere. Alle drei balte icb ontogenetiscb fiir 

 Abkommlinge der Geborkapsel. Aucb in phylogeiietiscber Hinsicbt leite ich 

 auf dieselbe zurtick und bin ferner der Ansicbt, dass sie nicht mit der Hyo- 

 mandibula der Fiscbe zu vergleicben sind." "Fiir das Operculum, eventuell 

 Operculum -f Stilus, der Urodelen wird dem ja wohl niemand mebr wider- 

 sprechen. . . ." 



