458 Thirty-fifth Report on the State Museum. 



smooth space at the center of about 5 mm. in diameter ; on the sides 

 of the lamellae, at right angles to the margin, are fine striations, about 

 15 in the space of 5 mm., there are also longitudinal striations; near 

 the margin of the calix the lamellae are denticulated, but on the sides 

 they are only obscurely crenulate or smooth. In general form this 

 species is very similar to H. scyplmlus, but that species has very prom- 

 inent spine-like denticulations. 



Formation and locality. Cornif erous limestone, New York. 



DIPHYPHYLLUM, Lonsdale. 



DIPHYPHYLLUM ADNATUM, U. Sp, 



Corallum sub-cylindrical, simple or compound, increasing by lateral 

 gemmation, frequently in contact for their entire length; exterior 

 with very regular annulations and concentric striae ; longitudinal striae 

 distinct ; diameter varying from 12 to 20 mm.; calix bell-shaped, 

 depth about 10 mm.; number of lamellae 50, of uniform thickness, 

 alternate lamellae continuing to internal wall ; space inclosed by verti- 

 cal wall, 3 mm. in diameter. 



Formation and locality. Corniferous limestone, Palls of the Ohio. 



DIPHYPHYLLUM CYLISTDRACEUM, n. Sp. 



Corallum cylindrical, growing socially but not in contact, increasing 

 by lateral gemmation, usually distant from each other from 5 to 10 

 mm.; external costae distinct, annulations and constrictions very strong ; 

 number of lamellae 45 to 50; space inclosed by interior wall 2 mm. in di- 

 ameter. This species most nearly resembles Diphypliyllum adnatum, 

 but the manner of growth is different, individuals of this speoies being 

 always more or less separated, while in that one they are in contact 

 usually their entire length. 



Formation and locality. Corniferous limestone, Falls of the Ohio. 



DIPHYPHYLLUM APERTUM, 01. sp. 



Corallum simple, sub-cylindrical, straight or curved, gradually or 

 more rapidly expanding; when decorticated presenting a distinct in- 

 vaginated appearance; length of one individual 60 mm.; calix bell- 

 shaped, diameter 20 mm., depth 10 mm.; number of lamellae from 60 

 to 70, of nearly uniform size at the margin, alternating below, the 

 principal ones extending to the vertical internal wall ; denticulations 

 prominent, 10 in the space of 5 mm.; inclosed internal area oval or 

 horse shoe-shaped, from 4 to 6 mm. in diameter, anterior side indented 

 by a deep, narrow fossette. 



Formation and locality. Corniferous limestone, Falls of the Ohio. , 



