1 92 PALAEONTOLOGY OF NEW YORK. 



Kjerdlf, F. A. Riemer and others, in ignorance of the preexisting name of 

 Hyolithes. 



In 1847 M. Barrande proposed the name Pugicncclus, and was followed by 

 Sanduerc.kr and others. 



In 1848 Mr. Salter described Theca anceps, from the Upper Silurian of the 

 Malvern Hills (Memoirs of the Geol. Survey, vol. 2, pp. 255-355, pi. 14, fig. 17). 



In 1850 Prof. d'Orbigny proposed the generic name of Vaginella, which 

 includes fossils of the genus Tiieca=Hyolithes as well as other forms. 



In 1857 the Chevalier Eichwald reproduced the generic description of his 

 genus Hvolithes, making reclamation of priority for the name (Beitr., in Bull. 

 Soc. Imp. des Nat. de Moscou, p. 146). 



In 1864 Prof. Lddwig included these forms under Cleodora, and Salter, in 

 1866, under the genera Clidotheca and Centrotheca in part. 



The American species of this genus have been. described in the following order: 



In 1847 the writer described Theca triangularis (Pal. N. Y., vol. 1), which 

 was subsequently re-described by Billings (1871) as Hyolithes Americanus ; the 

 name triangularis having been preoccupied by Portlock in 1843. 



In 1851 I indicated the occurrence of similar bodies at the base of the 

 Calciferous sandstone on the Escanaba river (Foster and Whitney's Report on the 

 Lake Superior Land District). These fossils are probably identical with those 

 subsequently described as Theca primordialis. 



In 1860 I described Pugiunculus? (Theca) aculeala, from the Goniatite beds of 

 Rockford, Indiana; in 1861 Theca primordialis, from the Potsdam sandstone of 

 the Mississippi Valley, and in 1862 Theca parviusculus, from the Hudson River 

 group, and Theca ligea, from the Upper Heldcrberg group. 



In 1861 Mi: i:it and Havden described Theca gregaria, from the Potsdam sand- 

 stone of the Big Horn mountain (Proceedings Phila. Acad. Nat. Sci.). 



In 1871 E. Billings described Hyolithes Americanus (= Theca triangularis, 

 Hall, 1847), and in 1874 H. communis, H princeps and H. excellens; all from the 

 Potsdam group. 



In 1872 Mr. Ford described Hyolithes impar, and in 1873 H. Emmonsi, from 

 the Potsdam group. 



