72 LOWER PENINSULA. 



examination of larger clusters it can be ascertained that the same 

 stems which usually send forth verticillate branches often also give 

 off single or only two or three branches. Mr. Billings considers 

 these as a different species, and names them Aulopora cornuta, but 

 frequently both forms are often seen as parts of one and the same 

 colony of stems. 



Found in the drift of Michigan, associated with fossils of the 

 corniferous limestone. It is common in the corniferous limestone 

 of Port Colborne, C. W. I also discovered several specimens fully 

 identical with the form of the corniferous limestone, in the Hamil- 

 ton group of Thunder Bay. 



Plate XXXIIL, Fig. 3. — The upper figures grouped together are 

 specimens from the drift, natural size. 



QUENSTEDTIA NIAGARENSIS. 



Tubes fully two millimeters in diameter, branching from a mother- 

 tube in irregular clusters, and diverging after a short space of con 

 tiguity with production of new lateral tubes. Lateral pores are large 

 and surrounded by a projecting rim. Longitudinal crests, or rather 

 rows of spinules, distinctly seen. Diaphragms are not preserved in 

 the specimens from Michigan ; others found in Iowa exhibit them. 

 Found in the Niagara group of Point Detour, Lake Huron, and at 

 Masonville, Iowa. 



Plate XXXIIL, Fig. 3. — Lower solitary specimen, found at Point 

 Detour. 



MICHELINIA, De Koninck. 



Including Chonostegites, Milne-Edwards. 



Compound polyparia formed of elongate, conical tubes, intimate- 

 ly connected in their whole length, or in rare instances with the con- 

 tiguity interrupted at intervals by constrictions. The tube channels 

 are in places of contiguity connected by lateral pores ; their cavity is 

 intersected by a succession of diaphragms of compound, irregularly 

 vesiculose structure, and the sides of the tubes are longitudinally 

 striate by numerous linear furrows, with intermediate rows of spinu- 



