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X. — The Genus Oldhamia (^Forbes) : its Character, probable Affinities, Modes 

 of Occurrence, and a Description of the Nature of the Localities in which it 

 occurs in the Cambrian Rocks of Wicklow and Dublin. By John Robert 

 KiNAHAN, M. D., Professor of Zoology, Department of Science and Art. 



Read April 12, 1858. 



±N certain schistose beds found at Bray Head, county of Wicklow, and Howtli, 

 county of Dublin, and which by the geologists of the United Kingdom are assigned 

 a place among the Cambrian system, or that which at present is universally re- 

 cognised as the lowest of the stratified rocks (whether, as some assert, itself a 

 system distinct from the Silurian; or, as others look on it, only a large portion of, 

 and not distinct from that formation), are found certain markings of a very 

 peculiar nature, occurring in mass, and now generally recognised as casts of 

 an animal assemblage, belonging either to the Polyzoan or Hydrozoan alli- 

 ance. To seek out the probable zoological relations of these, and to describe 

 the varieties which are found, is the intention of this paper. The fossils never 

 having been described or figured, with the exception of a few imperfect figures — 

 e. g., the small woodcut originally published by Sm Roderick Muechison in 

 " Siiuria," and which has been repeated in other works, such as the lamented 

 Hugh Miller's " Testimony of the Rocks," in which the locality whence the 

 specimen was obtained is misquoted as " Wray Head" for Bray Head — it is pro- 

 posed to figure here the more important varieties which occur; the wood- 

 cuts accurately taken from specimens obtained by myself at Bray Head, and 

 elsewhere, and which I have placed in the National Museum, at the Royal 

 Dublin Society, in this city. 



Although geologists are now perfectly agreed as to the organic nature of 

 these remains, it may not be unnecessary to recapitulate the points which dis- 



