' 



144 Correspondence — Prof. Hull— Dr. Traquair — Dr. Hinde. 



those of the northern hemisphere ; but to be effectual, the comparison 

 mus't be made by one who is well acquainted with the northern 

 deposits. F W. Hutton. 



Christchurch, N. Z., 12th Nov. 1889. 



CORAL-LIKE STRUCTURES FROM THE CULDAFF LIMESTONE, CO. 



DONEGAL. 



Sir, — I feel sure it will interest many of your readers to learn 

 that the peculiar Coral-like structures from the Culdaff Limestone 

 have recently been identified by Prof. James Hall, of Albany, and 

 Mr. Charles Walcott, of the U. S. Geological Survey, as belonging to 

 two genera of Palaeozoic Corals, namely, Columnaria and Tetradium ; 

 forms which are often found together in the Hudson Group of 

 America. These determinations have been arrived at, first, from 

 photographs of specimens from the Survey Collection, but after- 

 wards from five specimens selected and forwarded for examination. 

 The determinations were independently made, and serve to confirm 

 each other ; and Prof. Hall gives a detailed diagnosis of each 

 specimen. 



I may add that similar determinations have been arrived at by 

 Professors Dana and Ferd. Eoemer from an inspection of photo- 

 graphs only. Descriptions of some of these forms will appear in 

 the Geological Survey Memoir on Inishowen, North Donegal, now 

 passing through the press. The identification of these forms by such 

 experienced palaeontologists as those above named must be regarded 

 as of the highest importance in throwing light on the question of 

 the age of the Donegal crystalline rocks ; a question to which I 

 hope to return at a future time. Edward Hull. 



Geological Survey of Ireland, 

 14, Hume Street, Lublin. 



NOTE ON PHZYCTJENIUS, A NEW GENUS OF C0CC0STEIDJ3. 



Sir, — As my friend Dr. Hinde has just called my attention to 

 the fact that the name Phlyctcenias has already, under the form 

 Phlyctmiium, been given by Prof. Zittel to a genus of fossil Sponges, 

 I propose to substitute for it the term Pldyctcenaspis, concerning 

 which I can find no evidence of preoccupation. 



E. H. Traquair. 



RADIOLARIAN CHERT IN THE BALLANTRAE SERIES ( = LLAN- 

 DEILO-CARADOC) OF THE SOUTH OF SCOTLAND. 



Sir, — Sections of this rock, just received from Mr. B. N. Peach, 

 of the Geological Survey of Scotland, unmistakably show that it is 

 mainly composed of Eadiolarians. These bodies were first recognized 

 in the chert by my friend Prof. H. A. Nicholson, but their real 

 nature is only now conclusively shown in the sections sent me. 



21 February, 1890. G. J. HlNDE. 



