78 LOWER PENINSULA. 



mond's Island and of Point Detour, all in silicified condition- 

 Fig. 3 of the safne plate I considered sufificiently characteristic to 

 be described as a distinct species. 



HALYSITES COMPACTUS, N. Sp. 



Tubes oval, in chain-like, lateral conjunction, but these laminae are 

 so closely approximated, that no retiform loops are formed by them ; 

 they come in contiguity with each other from all sides, and leave 

 only small, angular, lacunose interstices in the corners of their inter- 

 section, which are not larger than the tube orifices themselves. By 

 this close approximation of the tubes on all sides many of them 

 become pressed into a polygonal form and resemble a Favosites, 

 from which they differ, however, in the absence of lateral pores. 

 The diaphragms of the tubes are closely approximated, flat, con- 

 cave or convex in the same specimens. Their diameter is about 

 one and a half millimeter. Found in the Niagara group along the 

 outcrops of the Upper Peninsula, at the shore of Lake Michigan. 



Plate XXIX. — Fig. 3 represents a lateral section and a surface 

 view of a specimen found at Epoufette Point. In a stratum of an 

 outcrop at the mouth of Manistique River this species is quite 

 common. 



SYRINGOPORA, Goldfuss. 

 Synon., Thecostegites, Milne-Edwards. 



Aggregated, sub-parallel, tubular polyp'stems, multiplying by lat- 

 eral budding, and at irregular intervals connected with each other 

 by short, transverse, tubular branchlets. The tubes are intersected 

 by numerous irregularly funnel-shaped diaphragms, and radiated by 

 twelve longitudinal rows of spinules, which arc sometimes obsolete. 

 The colonies of erect stems are at the base formed of horizontally 

 prostrate and attached ends, very much resembling the creeping 

 expansions of Aulopora, from which the young colonies are often 

 hard to be distinguished. 



