1 6 LOWER PENINSULA. ' 



orifices, but not prolongated across the interstices, which are 

 divided into a network of irregular angular cell spaces, or are, in 

 weathered specimens, of blistered aspect. Transverse diaphragms 

 subplane, often warped, closely set. Interstices between the tubes 

 larger than one tube diameter. Vesiculose plates of coenenchym of 

 irregular, coarser, or smaller size, frequently found partially de- 

 stroyed by decay, in which cases the tubes present themselves as 

 free, longitudinally carinated columns, held together by such of the 

 coenenchym as escaped destruction. Some of the specimens of 

 Sarcinula represented by Goldfuss are doubtless weathered speci- 

 mens of Lyellia. {Vide Sarcinula costata, Goldf. Tb. 24 f. 11.) 

 Growth in large convex expansions, with an epithecal 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. 



