180 REPORT ON THE STATE CABINET. 



Mr. Davidson has proposed the name Cyrtina. All the American species 

 hei-etofore referred to Cyrtia, and which have been reexamined, prove 

 to belong to Cyrtina. Of these we have C. pyramidalis in the Niagara 

 group, C. dalmani in the Lower Helderberg group, and C. rostrata in the 

 Oriskany sandstone. 



Three species are described in the present volume, from the rocks of 

 New York, viz : 



Cyrtina biplicala, from the Schoharie grit; 

 O. crassa (u. s.), from the Corniferous limestone; 



O. hamiltonioB, from the Hamilton group; and a variety of the latter 



from the Chemung group. 



A species from the Hamilton group in Iowa, C. curvilineata (1), is 

 noticed. 



The Genus Trematospira, proposed in Vol. Ill, Pal. N. Y., and pub- 

 lished in the Tenth Report on the State Cabinet, is represented in the 

 Hamilton group by two species : 



Trematosjpira gibbosa, 

 T. hirsuta. 



The Genus Rhynchospira is represented by only a single species, the 

 R. lej)ida. The R. nohilis from the Hamilton group, formerly referred to 

 this genus, presents some points which render its generic relations more 

 nearly with Trematospira. 



The genus Nucleospira is represented by a single species, the N. 

 concinna. 



The observations on the Genera Athtris and Meristella are as follows : 



GENUS ATHYRIS (M'Coy). 



The Genus Athyris was established in 1844 by Prof. M'Coy, upon 

 certain species separated from the TEREBRATULiE ; and when restricted 

 according to the original tj^pes of that author, includes a very natural 

 group of shells, but which nevertheless possesses many external features 

 in common with the later established Genera Merista and Meristella, 

 and from which the species are distinguished by important internal 

 characters. 



The shells of the genus are variable in form, being suborbicular, trans- 

 verse or elongate, subglobose or depressed, and sometimes subangular. 

 The typical species are depressed suborbicular. The structure of the 

 shell is fibrous ; the surface in most species is strongly marked by con- 



