PAL.-EONTOLOGY. 1 5 



Growth in large convex expansions, with an epithccal crust on the 

 lower, often concave side, or of lenticular or pyriform shape, with 

 conical basal side. Found abundantly on Drummond's Island, 

 Point Detour, and in other localities of Niagara exposures in Michi- 

 gan ; of frequent occurrence also in the drift of the Lower Peninsu- 

 la, and common in the Niagara group of Iowa. 



Plate II. — Fig. i. Surface view of a silicified specimen from 

 Point Detour, Lake Huron. Fig. 2. Side view of a weathered 

 specimen presenting the tubes as partially free columns connected 

 by the remains of the coenenchym vesicles. 



LYELLIA PAPILLATA, Nov. Spec. 



Tubes circular, not projecting above the general surface, crenu- 

 lated at the margins by twelve spinulose vertical crests. Diameter 

 of tubes about i|^ millimeter. Interstitial spaces as wide as a tube 

 diameter, or narrower, obscurely radiated on the surface by arrange- 

 ment of the coenenchym vesicles in conformity with the radial 

 crests of the inside. Diaphragms convex, with deeply depressed 

 margin, projecting within the orifices as rounded monticules, deco- 

 rated with granules. In weathered specimens the tubes stand out 

 as free, longitudinally carinated columns, as in the former species. 

 Mode of growth convex hemispherical above, flat or concave at the 

 lower side, which' is covered by a concentrically wrinkled epitheca, 

 or sometimes incrusting other bodies. Found abundantly in the 

 Niagara group of Point Detour and at Drummond's Island. 



Plate II. — Fig. 3 is a silicified specimen from Point Detour, 

 Lake Huron. 



LYELLIA DECIPIENS, Nov. Spec. 



Flat, undose expansions of laminated structure. Tubes one 

 millimeter wide, orifices not projecting, crenulated by twelve mar- 

 ginal crests. Diaphragms slightly convex. Interstitial spaces 

 usually larger than one tube diameter, their surface delicately 

 reticulated by circumscribed cell spaces, as in Heliolites, but in 

 vertical sections exhibiting a distinctly interlacing vesiculose struc- 

 ture, and not a tubular coenenchym. Found in the Niagara 



