HAMILTON GROUP. 



55 



equally distributed in the horizontal extension of a bed. We 

 may, in one part, for a distance of many yards, scarcely see 

 a fossil imbedded, when suddenly the same stratum becomes so 

 completely crowded with them that the whole rock mass is 

 a compact agglomeration of fossils, leaving no room for any in- 

 organic limestone particles between. It is Stromatopora pustuli- 

 fera in particular which is so abundant ; it grows in strumose, globu- 

 lar masses, often several feet in diameter, tightly crowded together, 

 and sparingly intermingled with other fossils. About 8 or lo feet 

 above this seam of Stromatopora pustulifera, another band follows, 

 which is equally rich in a different species of Stromatopora, Stro- 

 matopora cespitosa, a form of similar structure to the first, but 

 growing in clusters of ramified stems, or in more massive, globose 

 form, and with much larger pustules, and always with well-preserved 

 tissue fibres, which in Stromatopora pustulifera are nearly always 

 obscure. The massive forms of Str. cespitosa resemble Stromato- 

 pora monticulifera, but I do not believe them to be identical. As- 

 sociated with the Stromatoporas, a number of other fossils are 

 found in this locality, viz. : Favosites Hamiltonenis, Favosites digi- 

 tatus, Cyathophyllum juvenis, Cystiphyllum Americanum, Diphy- 

 phyllum rectiseptatum, Atrypa reticularis, Spirigera concentrica, 

 Terebratula Linklaeni, Pentamerus papilionensis, Spiriferfimbriatus, 

 Strophodonta erratica, Conocardium (a small form), Pleurotomaria 

 cavumbilicata, Phacops, Gomphoceras, Orthoceras, etc. A few years 

 since, on the shore in front of the rock bluffs of Petosky, lime-kilns 

 were built, which at the time of my visit were not so far finished 

 as to be in working order ; but the experiments made with the 

 rock on a small scale proved it to be well adapted for the pur- 

 pose. As a building-stone it has not much value ; it does not 

 sufificiently resist atmospheric influences. 



Prof. A. Winchell considers the position of these beds as 

 lowest in the rock series of Little Traverse Bay, but from my own 

 observation I am inclined to consider them as representing the 

 upper part of the series, and as equivalent with father strata 

 which by Winchell have been designated as buff magnesian 

 limestone. The rock bluffs just described are interrupted at 

 the location of Petosky village, and replaced by a drift terrace. 

 A quarter of a mile southwestward, close to the railroad bridge 

 across Bear Creek, a few ledges of the same rock seen in the 



