318 REPORT ON THE STATE CABINET. 



In the longitudinal section of the shell, fig. 7, it will be noticed that 

 the apex of the dorsal valve, or cardinal process, extends far into the 

 cavity of the ventral valve, while the cardinal muscle was 

 apparently attached just below the margin of the diajjhragm 

 or transverse septum of the opposite valve. The great 

 length and ventral extension of the longitudinal septum of 

 the dorsal valve is a remarkable feature. The mode of 

 articulation of the valves is much in accordance with the 

 recent Rhynchonellidse, except that the dental lamellce are 

 not distinctly developed. At the present time, however, I am far from 

 feeling satisfied regarding the true relations of this peculiar genus. 



The figures given illustrate all that we have observed in regard to 

 the interior structure of this genus, which is represented by several very 

 pretty species. I hope that the author of the generic name may feel 

 disposed to accept this contribution of facts regarding its more important 

 characters as aiding in the establishment of one of the most interesting 

 genera among the Brachiopoda. 



GENUS EICHWALDIA, Billings, 1858. 



Generic Characters — as emended. — Shells ovate or subtrigonal ; with or 

 without mesial fold and sinus. Ventral valve obscurely perforate on 

 the umbo; apex acute and entire, the space beneath it occupied by 

 an imperforate concave plate ; the interior of the rostral cavity lined 

 by a transverse septum or diaphragm, below which is the pedicel (1) 

 opening. Dorsal valve with a slender cardinal process, and a very 

 elevated medio-longitudinal septum. Valves articulating by a long 

 narrow groove in the cardino-lateral margins of the dorsal valve, in 

 which rest the elevated corresponding margins of the opposite valve. 

 Surface of the shell reticulate ; the texture solid and fibrous beneath. 



The American species known at present are : E. suhtrigonalis , Billings, 

 from the Lower Silurian, Canada ; E. coralifera, Hall, Niagara, New York ; 

 E. reticulata^ Hall, Niagara, Indiana; E. gihbosa, Hall, Niagara, Tennes- 

 see; E. concinna, Hall, Niagara or Lower Helderberg, Tennessee. 



ElCHWALDIA SUBTRIGONALIS, BiLLINGS. 

 Report on the Geological Survey of Canada, 1858, p. 192. 



ElCHWALDIA COBALIFERA, HaLL. 

 jiirypa coralifera, Hall ; Pateontology of New York, p. 281, 1852. 



This species occurs in the Niagara shale at Lockport and Rochester. 



