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having characters in common with the lungs of salamanders, and of 

 tlje reptiles improperly called doubtful reptiles. The lung or swim- 

 ming bladder of the Lepidostcus is not only cellular, but has also a 

 trachea, which extends the whole length of its anterior surface, and 

 communicates with a glottis, surrounded by ligaments, intended to 

 open and shut it, constituting an apparatus even more complicated 

 than what is found in many reptiles. M. Agassiz also adds, that the 

 heart has not the appearance of that of a common fish ; it is destitute 

 of the inflation named bulbus aorticus, so characteristic of fish, and 

 hence has much more the aspect of the heart of a reptile. 



With this fish, in its well-marked external characters, M. Agassiz 

 has compared the sauroid relics discovered at Burdiehouse, and, in 

 this inquiry, he has been assisted by the entire head of a large fos- 

 sil fish, preserved in the museum of Leeds. From the aid thus de- 

 rived, he has been enabled to establish a new genus under the name 

 of Megalichthys. With regard to the scattered and disjointed bones 

 found at Burdiehouse, it is conceived that they indicate a distinct 

 species, to which M. Agassiz has some time since given the name of 

 Megalichthys Hibberti. To the remains of another species of the 

 same genus discovei-ed near Glasgow, and distinguished by a greater 

 flatness of its teeth, M, Agassiz is disposed to assign the appellation 

 of Megalichthys fulcatus. 



In concludinar the account of this investigation, Dr Hibbert made 

 some observations on the importance in geology of selecting for pur- 

 poses of close comparison and analogy, animals subsisting in recent 

 times, which may be adjudged to bear the nearest affinity to races 

 long since extinct. In the present instance, the discrimination and 

 talents of M. Agassiz had been enabled to rescue from obscurity a 

 sauroid fish dwelling among the lakes and rivers of the most thermal 

 regions of America, and to render it elucidative of one of the earliest 

 states of our planet, when, in the language of this naturalist, fish 

 united in their particular organization the character of reptiles be- 

 longing to that class of animals which only appeared in far greater 

 numbers during a later epoch. 



