NOTICE OF PALEONTOLOGY. 



175 



Of the Genus Pholidops, two species, P. areolata (n. s.), and P. liamil- 

 tonice, occur in the Hamilton group. 



Of the Genus Orthis, the following species are described from the 

 Upper Helderberg group : 



Orthis jpeloris (u. s.), 

 O. lenticularis, 

 O. alsus (n. s.), 

 0. mitis (n. s.), 

 O. livia, 



Orthis similis (n. s.), 



O. cleobis (u. s.), 



O. idas (n. s.) = eryna,' 



O. jpropinqua. 



In the Hamilton group are the following species : 



Orthis solitaria, 

 O. lepida, 

 0. vanuxemi, 

 0. leucosia, 



Orthis penelope, 

 O. cycla3, 

 O. idoneus (n. s.), 

 0. tulliensis. 



In the Portage and Chemung groups, we have: 



Orthis carinata, 

 O. tioga (ii. s.), 

 O. imjpressa, 



Orthis leonensis (n. s.), 

 O. thiemei, and 

 0. l&mosia "? 



Under the Genus Streptorhynchus, several species heretofore described 

 are referred to Strophomena {Streptorhynchiis) cheinungensis , Conrad, under 

 which, as varieties, are arranged 8tro])homena hifurcata, S. arctostriata, S. 

 pectinacea, and Orthis perversa (Hall); Streptorhpichus pandora (Billings); 

 Orthisina arctostriata and 0. alternata (Hall) ; Orthis ineqimlis and 0. pravus 

 (Hall, Iowa Report.) The species is extremely variable, having a great 

 vertical and horizontal distribution, and appears under many phases. 



The Strophoinena rhmnboidalis (Wahlenberg) = S. rugosa (Rafinesque) 

 occurs in the Schoharie grit, and is abundant in the Corniferous lime- 

 stone, but is unknown in the Hamilton and Chemung groups. 



The Genus Strophodonta extends throughout the series ; and two 

 species, the *S'. demissa and S.perplana^ are found from the Schoharie grit 

 to the Chemung group inclusive. The species recognized in the Upper 

 Helderberg group are : 



Strophodonta demissa, 

 8. perplana, 



8. alveata, 



8. callosa, 



8. parva, 



8. crebristriata, 



Strophodonta inequiradiata, 

 8. patersoni, 



8. hemispherica, 



8. ineguistriata, 



8. ampla. 



^ See Sixteenth Report New York State Cabinet, p. 35. 



