560 Dr. J. E. Kinahan 07i the Genus Oldhamia. 



limits of each accurately, and to refer to their proper respective types the appa- 

 rently intermediate forms, which might otherwise tend to confusion. 



I have entered with some prolixity into many of the points connected with 

 these fossils, as, owing to the compai'atively limited district in which they are 

 found, most paleontologists have had but little opportunity of stixdying them 

 in the field, and hence probably has it arisen that this genus, from its geologic 

 position one of the most interesting we possess, has not been long ere this fully 

 described, although probably there is no fossil known which is so easily ob- 

 tained, occurs in such masses, or tells the history of its mode of life in more 

 unmistakable language. For a similar reason I have figured the species at some 

 length, the only species unfigured being that for which I have proposed a new 

 name, and of which it is nearly impossible to render the distinctive characters 

 in a woodcut. 



One other conjecture relative to the origin of these fossils should be ad- 

 verted to. Some have suggested that they may have been sea plants. This 

 opinion is now, I believe, abandoned by every one who has had an opportunity 

 of e.xamiiiing the fossils in situ; and furthermore, as has been shown, their ani- 

 mal connexion bears the stamp of the judgment of one of the greatest and most 

 philosophical naturalists of modern days, Edwakd Forbes. 



I have not adverted to the opinion of Continental writers, as these are ne- 

 cessarily most of them taken at second-hand from the description of the Eng- 

 lish authorities ; but I may mention that I find from Barrande that in Germany 

 the possible vegetable nature of the fossil is considered an open question. 

 D'Orbigny has declared for its animal nature, and the other opinion probably 

 but awaits the general diffusion of typical specimens to entirely vanish. 



The figures of this species hitherto published are most of them either ideal, 

 or else copies one of another, and are so scanty in detail that they are with 

 one or two exceptions hardly worth notice. Sir Roderick Murchison, as 

 already stated, gives a characteristic figure of Oldhamia antiqua (" Siluria," p. 

 180, 3rd ed.) Sir Charles Lyell has figured both species (" Manual of Ele- 

 mentary Geology," 5th ed., p. 453); it has been also figured in some of the 

 American books on the subject of geology. 



In describing Oldhamia radiata it will be remarked that no comparison 

 has been instituted between it and any living type : in fact, I do not know any 



