NOTICE OF PALJEONTOLOGY OF NEW YORK. 189 



From the Chemung group the following species are described : 



Rhynchonella {Stenodsma) eximia, 

 B. S. stephani (u. s.), 



R. S. duplicata, 



JR. S. contracta, 



R. S. orbicularis, 



R. S. sappho var. 



The Rhynchonella vemistula = R. cuhoides ? and R. subciiboides of former 

 reports is left under the Genus Rhynchonella, though with doubt regard- 

 ing its true relation. This species is known only in the TuUy limestone, 

 and occupies a very restricted vertical range. 



The Genus Leiorhtnchus is retained for such forms as L. limitaris and 

 L. qmdricostata, which present, among other distinguished features, a 

 division or bifurcation of the plications on the mesial fold and sinus. 

 The species recognized as belonging to this genus are : 



Leiorhynchus limitaris, 

 L. mysia (n. s.), 



L, quadricostata, 



L. multicosta, 



L. ins (n. s.), 



Leiorhynchus helloggi (u. s.), 

 L. sinuatus (n. s.), 



L. mesacostalis, 



L. globuliformis, 



L. dubius (u. s.). 



Under the Genus Leptoccelia, the L. aciitiplicata is the only species 

 recognized. 



The Genus Camarophoria has been observed in a single smooth species, 

 the C. eucharis, from the Upper Helderberg limestones. 



Some of the pentameroid forms, heretofore referred to the Genus Pen- 

 TAMERUS, are placed under new genera, on account of certain peculiarities 

 of their internal structure. The reasons for this course are given in the 

 following observations on the Genera Pentamerus, Pentamerella, Strick- 



LANDINIA, AnASTEOPHIA, AmPHIGENIA, RENSSELiERIA, etC, 



The Genus Pentamerus was proposed by Mr. Sowerby in 1813, to indi- 

 cate the peculiar internal structure of P. knightii, which is the type of 

 the genus. Dalman,* objecting to Sowerby's name, on the ground that the 

 shell was not five-chambered, proposed the name Gypidia as a substitute ; 

 but the latter has not been adopted by naturalists. 



Since that time much information has been obtained regarding the dis- 

 position of the internal parts of the shells of this genus, through the 



* Petrefacta Suecana, in Konigl. Vet. Acad. Handl., 1827. 



