24 BULLETIN NO. 2. 



GENUS ATHYRIS, McCoy. 



ATHYRIS SQUAMOSUS. (sp. IIOV.) 



Shell of medium size, broadly ovate transversely, or nearly cir- 

 cular in outline ; valves depressed, and showing externally live 

 heavy imbricating or overlaping plates, that were covered origin- 

 ally with short, coarse spines. Beaks depressed and closely approxi- 

 mate, that of the ventral valve rather the most prominent, and 

 projecting beyond the other, with a perforated extremity. 



Length from beak to base j^ inch ; greatest width of the valves 

 1^ inch ; thickness about fV inch. This unique form differs so 

 strongly from all others in the Carboniferous formation that a 

 comparison is unnecessary. 



Position and locality: Oolitic beds of the St. Louis limestone, 

 Monroe county, 111. 



No. 2527 of the Illinois State collection. 



Collector, A. H. Worthen. 



GENUS RHYNCHONELLA, Fischer. 



EHYNCHONELLA 2LLIN0IENSE. (sp. nOV.) 



Shell of about medium size, transversely ovate to sub-circular, 

 wider than long, Iront nearly straight in the middle, beaks ob- 

 tusely pointed. Ventral valve slightly elevated near the beak, 

 and depressed towards the front into a broad, shallow mesial 

 sinus, which is occupied by about eight sub-angular plications 

 that interlock in front with those of the opposite valve. There 

 are also from eight to ten similar plications on each side of 

 the sinus. 



Dorsal valve sharply depressed at the sides, nearly flat from 

 the beak to the front, which is elevated into a broad mesial fold 

 on which there are about eight elevated plications that interlock 

 with those of the opposite valve, and about the same number on 

 each side of the mesial fold. Length of an average size specimen 

 1% inch ; width ^ inch ; thickness in front about equal to the 

 length. The small individuals of this species, if found in Upper 

 Silurian strata, might be mistaken for R. Wilsoni. 



Position and locality : Coal Measures, Peoria county, 111. 



No. 2537 of the Illinois State collection. 



Collector, Mr. Gilford. 



GENUS LINGULA, Bruguiere. 



LINGULA VARSOVIENSIS. (sp. noV.) 



Shell of medium size, longitudinally oblong, more than one-third 

 longer than wide, with sub-parallel sides, the broadest part being 

 a little below the middle of the shell. 



