388 Miscellaneous. 



slip occurs in the frozen soil of the Siberian coast, which never thaws, 

 even during the greatest heat of the summer, to a depth of more than 

 2 feet ; and in this way, within a period of a century and a hidf, 

 five or six of these curious corpses have come to light from their icy 

 graves. — From a Report hy Mr. Lumley, H.M. Secretary of Embassy 

 and Legation, Russia, 1867. 



On the union of tlie Tympanic Bone with the Lower Jaw occurring 

 in the Marsupials dunng development, as a fresh proof of the agree- 

 ment of this hone with the os quadratum of the other classes of 

 Vertebrata. By Professor W. Peters. 



The articulation of the lower jaw in the Mammalia is effected, as 

 is weU known, by means of a condyle, which fits into an articular 

 cavity of the zygomatic process of the temporal bone, either directly 

 or by the mediation of an iuterarticular cartilage, whilst in the 

 other classes of Yertebrata the lower jaw is united, by means of an 

 articular cavity, with the condyle of a bone which, after Herissant's 

 example, is usually called the os quadratum. 



This bone is either articulated to the cranium (Birds, Lizards, 

 Snakes), or united to it by suture (Crocodiles, Tortoises, Batrachia). 

 In the former case it may assist in the formation of the tympanic 

 cavity and in the attachment of the tympanic membrane ; in the 

 second it always does so. This bone may be united to various parts 

 of the temporal bone, and to the pterygoid, sphenoid, and occipital 

 bones. Of aU these unions, that with the temporal bone, and, 

 indeed, with its squamous portion, is alone constant, whilst all the 

 others may be wanting. 



The question, vrith what part of the mammalian skull the qua- 

 drate bone is homologous, has given rise to many disputes, and has 

 been answered in various ways : — 



1. Herissant regarded the ascending ramus of the lower jaw as 

 the part corresponding to it. 



2. Tiedemann, Platner, and apparently Kostlin regard the qua- 

 drate bone as a part separated from the squamous (and petrous) por- 

 tion of the temporal. 



3. Geoffroy St.-Hilaire regarded the os tympanicum with the pro- 

 cessus styloideus as representing it. 



4. Oken, Cuvier, Blainville, Spix, Meckel, Cams, R. Wagner, 

 Kallmann, Stannius, Owen, and others interpret it as the os tym- 

 pxinicum. 



5. Reichert, 0. Schmidt, and Huxley declare that, as Cams had 

 previously supposed, the incus or the middle ossicle of the ear in the 

 Mammalia is the quadrate bone of the other Vertebrata. 



I had hitherto adhered to the opinion that the os tympanicum of 

 the Mammalia was homologous with the os quadratum of the other 

 Vertebrata, as also used originally to be indicated by J. Miiller, in 

 his lectures, whilst subsequently he used the expression " quadrate 

 bone." To me the proof of this interpretation lay in the similar 

 position of the bone in its relations to the tympanic cavity and 

 membrane, and in the union of the bone with the sphenoid occurring 



