26 LOWER PENINSULA. 



the centre to the peripheiy, which bear a deceptive Hkeness to 

 the radial lamellae, with intermediate vesicular cell spaces of the 

 calyx of a Cyathophyllum. 



This species is equally common in the upper part of the Helder- 

 berg group and in the Hamilton strata in Michigan, and in the 

 equivalent rock beds of other States east and west of it. 



Plate VI. — Figs, i and 2 represent two silicified specimens of 

 cylindrical growth. A part of the orifices in Fig. i is closed by 

 opercula plainly exhibiting the twelve marginal radial carinations. 

 Fig. 2 shows near the left margin opened tube channels with dimly 

 visible lateral pores. The central part of the specimen is formed 

 by the casts of tlie tube channels, with deep incisions in the place 

 of the diaphragms, and papillose prominences represent the 

 lateral pores. Fig. 3 is a weathered specimen of lenticular form, 

 having a dish shape presenting opened silicified tube channels, 

 intersected by diaphragms, and perforated by lateral pores. On 

 the centre of the specimen I fastened artificially a small horn- 

 shaped specimen, resembling the calyx of a Cyathophyllum. Fig. 

 4 is a calcified specimen, in the shape of a Dutchman's nightcap, 

 found in the Hamilton group of Thunder Bay. 



On Plate X., Fig. 2, a calcified specimen of similar growth to 

 that on Plate VI., Fig. 3, presents the angular tubes of a specimen 

 split open, with diaphragms and pores faintly indicated. The 

 latter belongs to the upper Helderberg limestone, and was found 

 in the drift of Ann Arbor. Specimen, Plate VI., Fig. i, is from 

 the corniferous limestone of Port Colborne. Fig. 2, Plate VI., is 

 found in the drift. Fig. 3, Plate VI., is from the Falls of the 

 Ohio. The small horn-shaped specimen in the centre is from the 

 drift of Ann Arbor. 



FAVOSITES EMMONSII, N. Sp. 



Synon., Emmonsia hemispherica, Milne-Edwards. 

 Favosites ALVEOLARIS, New York Reports. 



Tubes unequal, rounded-polygonal, from one to one and a 

 half millimeter in diameter. Tube channels longitudinally striate 

 by a cycle of twelve furrows ; of the intermediate band-like spaces, 

 each one bears a vertical row of horizontal squamae, which are 



