PALEONTOLOGY. 47 



Occurs in the Niagara group of Point Detour, and all along the 

 exposures of the south shore of the Upper Peninsula. 



Plate XVIII.^ — Fig. 3 represents a fragment of a large expansion 

 in silicified condition. Found near Seul Choix, on shore of Lake 

 Michigan. In mode of growth this species bears much resemblance 

 to Cladopora reticulata, Hall ; but the latter is a more delicately 

 built species, with smaller, nearly circular tube orifices. 



In the drift deposits of Michigan, specimens of Cladopora multipora, 

 Hall, are often met with. 



CLADOPORA LICHENOIDES, N. Sp. 



Irregularly undose, laminar expansions, covered by an epithecal 

 crust on the lower side, which is formed by prostrate, flattened 

 tubes, coalesced intimately and diverging horizontally from a cen- 

 tral apex. Toward their peripheral ends the tubes bend into a 

 suberect position and lose their flattened form, becoming rounded 

 and dilated near the orifices. These are sometimes nearly upright, 

 and join with acute margins, resembling an ordinary Favosites ; at 

 other times the obliquity of the orifices is more pronounced, and the 

 outer tube margins form an arched projecting lip, while the inner 

 margin merges into a narrow, common, interstitial surface. The 

 flattened tubes, forming the base of the expansions, connect by nu- 

 merous lateral pores situated on both edges ; the erect, more 

 rounded portions of the tubes have the pores irregularly dispersed 

 over their circumference. 



Diaphragms sparingly developed at irregular, remote intervals, 

 often closing the peripheral tube ends, under the form of opercula. 

 The tube cavity is generally smooth, without crests or longitudinal 

 furrows, which induced me to place this species with Cladopora, and 

 not with Alveolites, under which it might otherwise be classed 

 with propriety. Found frequently in the drift of Michigan. It 

 occurs in place in the corniferous limestone of the Falls of the Ohio, 

 in Canada and New York, etc. 



Plate XVII. — Fig. i gives a surface view of silicified specimens 

 from the Falls of the Ohio. Fig. 4 is a specimen found in the drift 

 of Ann Arbor, exhibiting the casts of tubes seen from the basal side 

 of an expansion. The flattened form of the prostrate channels, 

 with numerous short marginal pore connections, the gemmation of 

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