THE PTERICHTHY8. 115 



approaches the extremity, seems at last to pass 

 through the two portions of the tail, which is 

 invariably much more largely developed on the 

 under than on the upper side, so as almost to 

 appear crooked and ill formed. Have you ever 

 seen a shark or a dog-fish ? They are modern 

 examples of the cartilaginous series ; so is the 

 sturgeon ; and in all these the unequally lobed 

 form of tail prevails, although not to such an 

 extent as in these ancient fishes, in some of which 

 indeed the upper portion of the caudal fin is even 

 absent altogether. 



One specimen in this collection, totally dis- 

 similar as it was from all the others, attracted my 

 attention immediately. The pterich tliifs or winged 

 fish. If I had never perused Hugh Miller's pages, 

 I should hardly have supposed it to be a fish at 

 all. It had more the characters of a crustacean 

 or chelonian animal, to my inexperienced eyes ; 

 the body being covered with plates closely fitting, 

 like those of a lobster or tortoise. Although 

 smaller, it seems to be a more perfect example 

 than that from which Miller its first discoverer 

 took his description, the round head being as 

 distinctly developed as the sharp extended wings 

 and pointed tail. The colour, moreover, as in 

 all these Tynet fossils was ferruginous, instead 



