274 Scientific Intelligence. 
@ Discin ne of the Hamilton group are, Discina ‘minuta, huwibe 
. Elm 
Of the genus pss the C. Aurora ran .), occurs in mae Schoharie 
grit; in the Hamilton, are C. Hamiltone, er _— gregaria, ot 
the young of C, Ham militonee ; in the Chemung, C. Le 
Of the genus Pholidops, two eg P. areolata a “e and P. Ham- 
iltone, oceur in the Hamilton g 
‘ a 
Portage and Chemung groups, 0. panels, Tioya (n. s.), impressa, sa, Leo- 
nensis (n. 8.), Thieme, and leucosia ‘ed 
nder the genus jencole one. several —e heretofore deseri 4 
are referred to Str ophomena (Strept vie tis nan ungensis Conr my 
eninonaaich homboidalis (Wahlenberg)=S, rugosa (Rafinesque) 
oe in the Schoharie grit, and is abundant in the Corniferous limestone, 
but is unknown in the Hamilton and Chem ups. 
The genus ae extends throughout the series; and tw ones 
the S. demissa and S. perplana, are found from the Schoharie grit 
the Chemung group inclusive. The species recognized in the ae 
Helderberg group are, S. demissa, perplana, alveata, callosa, parva, 
striata, inequiradiata, Patersoni, hemispherica, inequistriata, ampla ; in ae 
the Hamilton group, S. concava, perplana Conrad (which has peeee 
scribed under the names St rophomena perplana, S. plurisiriata 
i gees Con rad; and as S. nerovsa, S. crenistriaia and’S. to 
Hall); demi , nequistriata, jumia ; in the Chemung, co 
ta (n.s.), mucronata, celata (n. s.), perplana var. nervosa, demissa. 
In the genus Chonetes, we find verified in a very satisfactory ee 
the observations made by Count von Keyserling, in regard to a 
or spine- in the area of the ventral valve. pa 
are directed from the hinge-line toward the apex of the valve, pre 
parallel to the sides of the trian fissure. They appear on the ha 
} gated tubular er which may the 
The jr, areal of 
