I08 LOWER PENINSULA. 



own complete wall. Surface of calyces expanded, discoid, with an 

 abrupt but shallow central pit, the reversed bottom of which con- 

 ically projects, covered by the central ends of the radial crests. 

 Lamellae linear, subequal, from sixty to seventy in the circum- 

 ference of a calyx, crenulated by transverse trabeculae (bars), which 

 are the ends of lateral, arched carinae decorating the side faces ; 

 about fourteen carinae on the length of one centimeter. Inter- 

 stitial spaces filled with vesicles arranged in arched rows run- 

 ning diagonally across the carinations. Central area traversed by 

 transverse, larger plates, which are much intersected by the ver- 

 tical lamellae. The structure of this coral is identical with Cyatho- 

 phyllum Hallii, from which it differs principally in its cespitose, 

 compound growth. Found frequently in silicified condition in the 

 drift, connected with fossils of the corniferous limestone. 



Plate XXXVIII.' — Fig. 4 represents a fragmentary specimen 

 from the drift of Ann Arbor. 



CYATHOPHYLLUM RADICULA, N. Sp. 



Small single polyp stems, about one centimeter in diameter, coni- 

 cal at the base, cylindrical in their prolongation, annulated by 

 numerous sharp constrictions caused by periodical interruptions in 

 the growth of the cells, which commences again with contracted 

 base from the centre of the old cells. The bases of the stems are 

 strongly attached to other bodies, and the attachment is often 

 strengthened by excrescences from the sides of the stems. Calyces 

 not as deep as wide, with erect, ascending sides, slightly expanded 

 near the margins, and. surrounded by about sixty alternately larger 

 and smaller crenulated lamellae. Bottom of cells flat, formed of 

 a smooth or faintly carinated or granulose transverse diaphragm ; 

 in some other specimens the lamellae extend to the centre, and the 

 bottoms of the cells are more rounded, concave. A septal fovea 

 is rarely indicated. Found in the Niagara group of Drummond's 

 Island, at Point Detour, and in the Niagara group of Iowa. 



Plate XXXIX., Fig. 3. — The left-hand, outer vertical row of 

 specimens is from Point Detour ; the central row represents speci- 

 mens from Masonville, Iowa ; the right-hand row may be a different 

 species. It occurs in the Niagara group of Louisville, and of Charles- 



