176 DE. O. BAUR. 



lower jaw and the quadrate of Amphibia are homologous 

 with the malleus and incus of the Mammalia loses every 

 foundation." 



In a later communication (" Ueber der Gehorknockelchen 

 der Schildkroten, Eidechsen, und Schlangen," ' Monatsber. d. 

 Berl. Akad./ January, 1869) Peters states that in an embryo of 

 Hemidactylus the cartilaginous thread passing from the 

 malleus bends round close to the quadrate, and sinks into the 

 lower jaw. Therefore Peters recognised the malleus in the 

 Sauropsida long before Dollo. 



I pass now to my own researches on the subject. As is well 

 known, the theory is to-day nearly universally taught, especially 

 in England, that the columella " and its appendices" are modi- 

 fications of the second, and not of the first, visceral arch. Thus 

 Parker 1 has lately written, " After long years of labour and 

 much vacillation of mind on the matter, I am now quite satis- 

 fied that the stapes, a little stirrup-bone of the ear drum, is the 

 uppermost element of the second or hyoid arch." 



To these views Huxley's 2 researches on the stapes of 

 Sphenodon especially contributed. 



According to Huxley the hyoid cartilage rises up behind the 

 quadrate till it has nearly reached the skull, and then appears 

 suddenly to be bent in the form of a small scroll with a pos- 

 terior concavity. This scroll is due to the widening out of the 

 hyoid bone, which forms a cartilaginous plate. On the inner 

 side this plate is produced into the stem (base) of the stapes, 

 and soon ossifies. According to Huxley, therefore, the upper 

 stapes-cartilage is nothing else than the inner end of the hyoid 

 arch. The stapes and its appendices belong absolutely to 

 this arch, and have nothing whatever to do with the mandibular 



arch. 



On the other hand, Peters says : The connection of the hyoid 

 arch with the stapes-cartilage (malleus) is not a primary but 



1 W. K. Parker, 'On Mammalian Descent,' London, 1885, p. 43. 



2 T. H. Huxley, " On the Representatives of the Malleus and Incus of the 

 Mammalia in the other Vertebrates," ' Proc. Zool. Soc.,' London, 1869, 

 p. 391. 



