Dr. J. E. KiNAHAN on the Genus Oldhamia. 



559 



with, has been already referred to, and point, as there stated, to a very different 

 character in the sea bottoms, of which eacli was an inhabitant. The non-occur- 



FlG. 9. Oldhttmia aniiqua. — The 

 elongated form still further drawn out 

 by cleavage. From Bray Head. 



Fig 10. Oldhamia antiqva. — Two polypidoms overlapping, exhibit- 

 ing central axis, elongated branchlcts, and oviferous capsules. Gray- 

 stones, 



rence of the former species at Ilowth may be thus accounted for. The beds 

 there, few in number as they are, in which I succeeded in detecthig Oldhamia 

 aniiqua, are all soft slate, splitting readily into thin laininse, such, in short, as 

 would result from a muddy deposit. The rock in which the Carrickmount 

 Reilly specimens are embedded is similar in character ; and all the specimens 

 thence are either Old. antiqua, or Old. discreta ; if Old. radiata exist there, I 

 would not expect it should be got in these beds. This difference in habitat is 

 a point which might be worthy of consideration with regard to the division of 

 the genus. 



There is a state of Old. radiata which is frequently, in museums, mistaken 

 for Old. antiqua, where the stars overlap one another in a sort of alternate man- 

 ner ; the absence of the median axis and the irregularity of the branchlets 

 may distinguish it. 



Some have, on a hasty examination of an imperfect series of specimens, sug- 

 gested that probably the two species established by Forbes are really but one. 

 An examination of the fossils in position in the field will show the absurdity of 

 this idea ; the differences between the two becoming more and more evident on 

 examination of a lengthened suite of the fossils, as this enables us to define the 



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