THE ANNALS 



Am) 



MAGAZINE OF NATURAL EISTOEY. 



[SIXTH SERIES.] 

 No. 40. APEIL 1891. 



XXXIII. — On some new or imperfectly -known Species qfStro- 

 matoporoids. By H. Alleyne NICHOLSON, M.D., D.Sc, 

 Regius Professor of Natural History in the University of 

 Aberdeen. — Part IV. 



[Platss VIII.-X.] 



In the present paper I propose to give short descriptions of a 

 number of Stromatoporoids from the Palfeozoic rocks of North 

 America, some of which are well known as occurring in 

 deposits of the same age in the Old World, while others are 

 new. Most of the forms in question have been collected by 

 the officers of the Geological Survey of Canada, and have 

 been entrusted to me by Mr. Whiteaves for examination and 

 description. Among these is an interesting series of Stroma- 

 toporoids from the Devonian rocks of Manitoba. By the 

 kindness of Mr. Whiteaves I have also been put in possession 

 of examples of two of the species of Stromatoporoids described 

 by Professors Hall and Whitfield from the Devonian rocks of 

 Iowa (' Twenty-third Ann. Rep. of the State Cabinet,' 1873). 

 One of these, viz. Stromatopora expansa^ Hall and Whitf., 

 proves to be a species of Actinostroma, and will be described 

 and figured here ; the other, viz. Stromatopora ( Ccenosiroma) 

 incrustanSf Hall and Whitf., is a species of Stroinatopoi-ella, 

 Ann. & Mag. N. Hist. Ser. 6. Vol vii. 22 



