NOTICE OF PALiEONTOLOGY OF NEW-YORK, VOLUME IV. 151 



The name AmboC(ELIa is continued, being regarded as presenting suffi- 

 cient distinction from Spirifer A ; and in the Hamilton group are recognized ; 



Amlocoslia umbonata, 

 A. preumbona. 



In the Chemung group, A. umbonata var. grcgaria. 



On page 263 of the volume are some observations on the Genus Cyrtia 

 of Dalman, and Cyrtina of Davidson. 



So long since as in 1858, Mr. Davidson, in his Introduction to the Study 

 of the Brachiopoda, had expressed some doubts as to the value of the Genus 

 Cyrtia of Dalman ; and later investigation had shown that the typical 

 species of that genus does not differ from Spirifera. At the same time, 

 some forms usually referred to the Genus Cyrtia possess a peculiar modifi- 

 cation of the dental plates, with a largely developed median septum and 

 punctate structure of the shell. For these forms, Mr. Davidson has proposed 

 the name Cyrtina. All the American species heretofore 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 Hel- 

 derberg group, and C. rostrata in the Oriskany sandstone. 



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

 York, viz : 



Cyrtina bipHcata, from the Schoharie grit ; 

 C. crassa (n. s.), from the Corniferous limestone; 



C. hamiltonice^ from the Hamilton group ; and a variety of the 



latter from the Chemung group. 



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

 noticed. 



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

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

 Hamilton group by two species : 



Trematospira gibbosa^ 

 T. hirsuta. 



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

 jR. lepida. The R. nobilis from the Hamilton group, formerly referred to 

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

 nearly with Trematospira. 



The Genus Nt'cleospira is represented by a single species, the N. 

 wncinna. 



