80 THE ASTEIIOLEPIS, 



The problem coiild not be wrought by the remodel! ing oi 

 an old house : the only mode of solving it would be by the 

 erection of a new one. 



There is one important characteristic of the jaws of this 

 ancient ganoid, which, although common to the jaws of some 

 of the other and better-known Palaeozoic Celacanths, such as 

 the Iloloptychius, seems to have hitherto escaped the notice 

 of ichthyologists. Cuvier, in his description of the generic 

 peculiarities of the alligator, specifies, £is one of the most re- 

 markable, a certain mechanical arrangement through which 

 the fourth tooth in the lower jaw is received, when the mouth 

 closes, into a deep cavity hollowed in the upper jaw for its 

 reception. A similar peculiarity occurs in the jaws of the 

 Lepidosteus, and forms one of the links with the Saurians 

 which establish its herpetological relationship. " The inter- 

 maxillary of the Lepidosteus^^ says Agassiz, " is a small bone, 

 pierced wdth two holes for the admission of the anterior pro- 

 jecting teeth of the lower jaw." Now, it is an interesting 

 circumstance, that in the Asterolepis^ the huge reptile teeth 

 which stand up over and behind the ichthyic ones were re- 

 ceived, as in the alligators and the Lepidosteus, into deep 

 cavities hollowed in the opposite jaws ; but the arrangement, 

 instead of being restricted to two teeth, as in the recent rep- 

 tile, or to a small group of teeth, as in the existing reptile- 

 fish, pervaded the entire jaw. All the large teeth had deep 

 cavities hollowed to receive them, as the scabbard receives 

 the sword ; and these scabbard-like hollows occurred in most 

 cases so close beside the reptile teeth of the opposite jaw, 

 that each tooth formed one of the sides of each hollow ; and 

 the base of the teeth springing from the same level as the 

 bottom of the hollows, bore the appearance of teeth placed 

 in sockets twice too big for them.* I may add, that there 



* Some of the reptile teeth of the HoloptycTiii of the Coal Measures, as 

 filiown in specimens from Gilmerton and Burdie House, had great depth 



