28 H. B. POLLARD. 



Cavier (1814) dealt with the upper jaw of fish and came to the 

 conclusion that the maxillary bones (labiaux ou mystaces) and inter- 

 maxillaries correspond to the two labials of Squatina and other sharks, 

 while in the Rays the intermaxillaries are represented by the small 

 cartilage in the nasal lobe, and the maxillaries by the " Schadelflossen- 

 knorpel." 



On the maxilla of Teleostei he remarks : " Since the labial bone is 

 unprovided with teeth in almost all the fish, it has little resemblance to 

 the ordinary maxilla ; but in order to be convinced as to its nature, it 

 is enough to observe it in the trout or salmon, and thence to follow it 

 in its various forms" (I may here remark that the Teleostean maxilla 

 only partly corresponds to the maxilla of other vertebrates e.g. 

 Polypterus, where it is mainly a " suborbital " bone. 



On the Siluroids he remarks : " The intermaxillary, without a pedicle 

 (ascending process), is situated under the anterior, more or less broad- 

 ened edge of the skull and at each of its extremities is a small maxilla, 

 which, becoming flexible, is prolonged into a long filament or barbel : 

 in a word, the principal barbel of Siluroids is their maxilla prolonged." 

 As to Chimaera : " In the thickness of the lip are found three bones 

 (cartilages), which one recognises as the intermaxillary, maxillary, and 

 the palatine arcade ; this last is entirely suspended by muscles and 

 ligaments, without articulating with anything." 



Subsequent investigation has confirmed the remarks of Cuvier to 

 a wonderful extent. 



Rathke (1823) compared the labials of Petromyzon to the 

 " Knorpelriemen " of Amphioxus (I quote from memory of the text). 



Johannes Muller (1835) criticised Cuvier's accounts and views and 

 attempted to show that the labials are structures not belonging to the 

 general plan of the vertebrates, and that the upper- jaw of sharks 

 corresponds to the upper jaw of other vertebrates. " The tooth-bearing 

 cartilage of Plagiostomi can be nothing else than the upper jaw 

 (maxilla), while the labial bones are, as we have already shown, accessory 

 pieces. Probably in the tooth-bearing cartilage, maxilla and premaxilla 

 are united " The palatine arch of e.g. Teleostei is, according to Muller, 

 represented by accessory cartilages in Narcine and other fish. Midler 

 makes many valuable comparative observations, and gives a complete 

 account and figure of Callorhynchus. His views have not met with 

 acceptance, and have been abandoned since Hertwig's researches on 

 dermal bones. 



