DIAGNOSTIC FEATURES OF ALLIED GENERA. 28] 



these two are exclusively European. C. magnificum is the most abundant 

 and widely distributed of any of these. According to Dana, it is charac- 

 teristic of the Corniferous.* It was obtained by Billings from Walpole. 

 township, Canada West, and by Rominger and others from the Upper 

 Helderberg group of Mackinac island ; falls of the Ohio ; Charleston land- 

 ing, Indiana; and distributed through the drift. C. belli is from the 

 Upper Silurian (Clinton; of Manitoulin island, lake Huron. C.pondero- 

 mm " occurs rarely in the Upper Helderberg limestones, but is abundant 

 in certain layers of the Hamilton group of Thunder bay." It occurs also 

 in the same formation at Little Traverse bay, and has been met with in 

 the drift. C. greenei is from the Niagara limestone near Louisville, Ken- 

 tucky. 



The range of the genus is thus through the Upper Silurian and two 

 lower divisions of the Devonian, reaching its maximum development in 

 the Upper Helderberg. Ushered into the warm molluscan seas, surviv- 

 ing the changes which inaugurated the Devonian, finding here conditions 

 most favorable for its development, by the close of the Hamilton its life 

 energies had been spent, and, shrouded only by. the sea bottom's slime 

 and ooze, it passed from scenes of active existence. 



Note: In replyto a letter of inquiry concerning the structure of certain of these corals, Professor 

 Jamos Hall writes as follows: 



" In regard to Chonophyllum magnificum, I may say that I know no other coral having the same 

 type nt structure. 1 have had slices cut from well preserved specimens in several directions, ami 

 all show a peculiar membraniferous structure such as I have been unable to obtain from any 

 other cyathophylloid corals or from any other coral which I have examined. When I referred 

 species to Chonophyllum I had not made sections for critical study. I have since concluded that 

 Chonophyllum niagarense should 1»- referred to Cystiphyllum, though this one and some other forms 

 present a very unusual appearance for that genus. Of C. (Ptyehophyllum) ellipticum, I do nut at this 

 moment recall the structure. All these specimens are now in the American Museum of Natural 

 II istory, in tie- city of New York, and have been out of my hands for sixteen years. 



" I cannot at this moment recall the characterswf C. vadum and C. eapax, nor do I think I have 

 had sections made of them. I cannot speak positively, but 1 greatly doubt whether they will shew 

 the peculiar superimposed membraniform layers or tissue characteristic of C. magnificum." 



New YoitK State Museum, December 26, 1893. 



* Manual of Geology. 1880, p 261. 



