124 LOWER PENINSULA. 



crests. The interlamellar interstices of the peripheral area are 

 traversed by vesiculose plates ; the central area, principally formed 

 by transverse diaphragms, is not defined from the peripheral cycle 

 by an internal wall. Gemmation calycinal, producing single forked 

 branches or a number of young calyces sprouting at once from the 

 end cells. Occurs in the upper Helderberg limestone of Mackinac, 

 and in the corniferous strata of Canada, New York, Ohio, and in 

 the Western States ; likewise found frequently in the drift of the 

 Lower Peninsula. 



Plate XLVI., Upper tier. — The left-hand figure represents a 

 specimen found in the drift, with tubes smaller than usual ; it is in 

 all probability identical with DipJiypJiylhini strawineiun, Billings. The 

 two lower figures are different views of one specimen with larger 

 tubes, agreeing with the type form of Eridophyllum Simcoense, 

 described by Billings. It was found in the corniferous limestone 

 of Caledonia, N. Y. 



DIPHYPHYLLUM RECTISEPTATUM, N. Sp. 



Cylindrical, closely aggregated, subflexuose stems, from five to 

 seven millimeters in diameter. Calyces with erect, vertically ascend- 

 ing side walls, and a broad bottom formed by flat diaphragms de- 

 pressed in their circumference and smooth in the centre. Lamellae 

 stout, alternating in size, not crenulated, about thirty-six in the 

 circumference of a calyx ; the larger ones extend over the marginal 

 parts of the diaphragms. Diaphragms remarkably regular, extend- 

 ing nearly across the entire width of the stems, meeting near the 

 outer walls with a very narrow peripheral cycle of more minutely 

 cellulose structure, formed by intersection of the interlamellar 

 spaces with ascending rows of small, transverse, vesiculose plates. 

 The species has much resemblance to Diphyphyllum latiseptatum 

 of McCoy. Occurs in the lowest horizon of the Hamilton group, 

 near Craford's quarry, at Middle Island, Presque Isle Lighthouse, 

 etc. Not figured. 



