178 DR. G. BAUR. 



My material consisted of three specimens of Sphenodon, 

 preserved in alcohol : for two of these {a and b), from the 

 Museum of Yale College, I have to thank Mr. O. C. Marsh ; 

 the third (c) came from Prof. B. G. Wilder, of Ithaca. 

 The specimen a measured about 360 mm., the tail being 

 regenerate ; b measured 290 mm., and c 210 mm. In the 

 specimen a I have dissected out on both sides the part con- 

 cerned, of b and c only that of the right side. Examined with 

 a lens the hyoid arch is seen to be close to the cartilaginous 

 part of the stapes ; in fact, was in part fused with it. In order 

 to be quite certain of this, series of sections from the prepara- 

 tions of a and b were prepared. These show that the hyoid 

 arch is free from the real malleus, although it applied itself 

 closely to the front edge of the stapes-cartilage. The relations 

 in section are, certainly, not so distinct as I had expected; 

 and the examination of Sphenodon alone had made the 

 settlement of the point impossible. But that the hyoid has, 

 in fact, nothing to do with the stapes is very clearly seen in 

 Tarentola annularis (Platydactylus segyptiacus). 

 Here the hyoid arch is just as perfect as in Sphenodon, but 

 it does not enter into so intimate a connection with the stapes- 

 cartilage. From the long process of the malleus {" infrasta- 

 pedial" of Parker), however, there passes downwards a thin 

 fibre, to sink into the lower jaw ; this is the epimandibular 

 portion of Meckel's cartilage (" ceratohyal " of Parker). 

 Here, therefore, we have a similar condition to that described 

 by Parker 1 for the crocodile. 



From the observed facts, there is no doubt that the malleus 

 of Sphenodon, and therefore of all the Sauropsida, is not derived 

 from the hyoid arch, but from the mandibular arch. Albrecht 2 

 has already maintained on logico-theoretical grounds, that the 

 wrongly so-called hyomandibular (ceratohyal) is nothing else 

 but the dorsal portion of the first visceral arch, that is of 

 Meckel's cartilage. My own researches on Sphenodon, and 



1 W. K. Parker, " On the Structure and Development of the Skull in the 

 Crocodilia," ' Trans. Zool. Soc./ vol. xi, 18S3, pi. 68, fig. 19. 



2 P. Albrecht, ' Sur la valeur morphologique de la trompe d'Eustache,' 

 Bruxelles, 1884. 



