PALEONTOLOGY. 1 5 



PLASMOPORA ELEGANS, Hall. 



Synon., Heliolites elegans, Hall. 



Heliol. spinipora, Hall. 

 Plasmopora SCITA (?) Milne-Edwards. 



Tubes a little over half a millimeter wide, radiated by twelve prom- 

 inent longitudinal rows of spinules obliquely directed upward, and 

 nearly reaching the centre. Diaphragms complicated and anchy- 

 losed with the spinulose projections. Coenenchym composed of 

 very stout vertical lamels, with delicate transverse leaflets intersect- 

 ing them. Intervals between the tubes about as large or larger 

 than a tube diameter. Growth pyriform or globular. Found in 

 the drift deposits of Michigan. Common in the Niagara group of 

 New York, Indiana, and Kentucky. 



Plate III., Fig. 2. — The two lower specimens, both silicified, are 

 from Paul's Station, Indiana. 



LYELLIA. 



Milne-Edwards. 



Visceral tubes circular, with orifices projecting above the general 

 surface, radiated by twelve conspicuous vertical rows of spinules, 

 and transversely septate by subplane diaphragms. 



Coenenchym abundant, formed of convex, vesiculose, horizontal 

 plates of unequal size, extending in interlacing layers across the 

 intertubular interstices, and inclosing blister-like cavities much 

 resembling the vesiculose tissue of a Cystiphyllum. 



LYELLIA AMERICANA, Milne-Edwards. 



Synon., Heliolites macrostylus. Hall. 



Tubes \\ to 2 millimeters wide, radial crests almost extending 

 to the centre, and decurrent on the outer projecting part of the 

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