178 THE MICROSCOPE. 



The microscopist interested in the study of organic structures 

 will find many of our fossil corals extremely available, and exqui- 

 sitely delicate, in their minute details. " The Avhole order of cup- 

 corals {Hugosa) is well represented in the west, and thin transverse 

 sections reveal their internal structures with a clearness not dreamed 

 of ten years ago by palteontological investigators. No other method, 

 in fact, suffices for the demands of modern investigation. One of 

 the commonest and most beautiful of the cup-corals is Hcliophyllum 

 JIalli, found in the Hamilton group from central New York to 

 Michigan. The cliffs at Petoskey afford it abundantly, but some 

 Ontario localities yield handsomer and more numerous specimens, 

 especially Widder (on the railway) and the creeks through the 

 township of Bousanquet. Another exquisite form is Acervularia 

 Davidsoni, found in extreme abundance at Petoskey and in the 

 region about Thunder Bay, but known from Ontario to Iowa City. 

 Petoskey and the Thunder Bay region yield also three genera of 

 corals belonging to the family of StroniatoporidcB. Of these, Cccno- 

 stroma and Idiostroma were first described from Michigan, and the 

 former affords, in thin sections, very interesting specimens. All 

 these admit of only a very low power. 



But the forms lately embraced in the genus AlonticuJipora 

 (mostly ChiBtetes lycopcrdon of the older writers), are so minute in 

 their structure as to render the microscope indispensable. These 

 are chiefly Lower Silurian corals, and occur in extreme abundance 

 in southern Ohio, in central Kentucky and central Tennessee. 

 They have recently been studied with -much detail by Professor 

 Nicholson, formerly of Toronto, now of St. Andrews, Scotland. Mr. 

 U. P. James, of Cincinnati, is also engaged on them, and Mr. W. P. 

 Cleveland, of Higginsport, Ohio, prepares beautiful specimens. 

 The minute structures of fossil corals in general, are under investi- 

 gation by Prof. James Hall, of Albany, who has had prepared a 

 large number of marvelously fine specimens. 



A different class of subjects is furnished by Eozoon Canadense, 

 an object whose organic nature is not even yet completely settled. 

 Dr. Dawson, of Montreal, has labored extensively on its minute 

 structure and systematic relations, and has written a charming little 

 volume, "The Dawn of Life," on this subject. It has also engaged 

 the attention of the renowned microscopist, Dr. W. B. Carpenter. 



Still another direction in which the American microscopist may 



