. Annual report of the regents of the university of the state of New York on the condition of the State Cabinet of Natural History and the historical and antiquarian collection annexed thereto. Science. NOTICE OF PALEONTOLOGY OF NEW-YORK, VOLUME IV. 157 MERISTELLA (MERISTINA) Showing the first volution of the spiral lamellae.' The same characters have also been observed with equal distinctness in M. nitida of the Niagara group. In neither of these species is there any indication of accessary lamellae as in Athyris, nor evidence of the exten- sion of the loop beyond the point e; and we
. Annual report of the regents of the university of the state of New York on the condition of the State Cabinet of Natural History and the historical and antiquarian collection annexed thereto. Science. NOTICE OF PALEONTOLOGY OF NEW-YORK, VOLUME IV. 157 MERISTELLA (MERISTINA) Showing the first volution of the spiral lamellae.' The same characters have also been observed with equal distinctness in M. nitida of the Niagara group. In neither of these species is there any indication of accessary lamellae as in Athyris, nor evidence of the exten- sion of the loop beyond the point e; and we are therefore induced to believe that the simple character of the spires in these forms will constitute another distinction, which may conveniently be termed Meristina. The G-enus Atrypa, as applied to forms strictly congeneric with. Atrypa reticularis, embraces but few species, and these are regarded by some palaeon- tologists as merely varieties of still fewer species. In this volume, the Atrypa impressa of the Schoharie grit is continued as a distinct species : although resembling the A. reticularis in general features, it presents a wide departure from the forms of that type in other strata; and if we are to regard these varieties as due to physical causes, the nature of the sediments, etc., then there is reason to believe that in other instances the same physical influences have produced changes which are recognized without hesitation as of specific value. The Atrypa reticularis, in its various phases, occurs in the Corniferous limestone, the Hamilton and Chemung groups. The Atrypa spinosa (Hall), or Atrypa aspera ( Schlotheim), is recognized as a very distinct and well-marked species, occurring in the Corniferous limestone, Hamilton and Chemung groups. In the Hamilton group it is more abundant and better preserved than in any other forma- tion ; and occurring in the same beds with A. reticularis, it never approaches that one in character ; there is no difficulty in distin
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