The Galena and Maquoketa Series. — Sardeson. 185 
4. Rhynchonella var. laticostata W. & S.. Rhynchotrema 
iiixqai.onlois var. laticostata W. &. S., lo?. cit., fig. 26-29; 
Ehi/nchoneUa sancta Sardeson, Bull. Minn. Acad. Nat. Sci., 
vol. 3, p. 3.33, pi. 4, f. 19-20, is associated with R. increbescens 
H. in the Orthisina bed (6). 
5. Rhytichonella plena (]ia.\\), Atrypa plena Hail, Pal. N. 
York, vol. 1, p. 21, pi. 4 bis, f. 7 a-e (1847) is rare in the 
Fucoid bed (5) in Minnesota. 
6. Rhynchonella capax (Conrad), A fry pa capax Con., 
Jour. Acad. Nat. Sci., Phila., vol. 8, p. 264, pi. 14, f. 21 (1842) ; 
Rhychonella capax Billings, Geol. Canada p. 211, f. 213 (1863) : 
R. capax Whitf., Geol. Wisconsin, vol. 4, p. 263, pi. 12, f. 
26-27 (1882); Rhynchotrema capax W. & S., Final rep. Geo. 
Sur. Minnesota, p. 462, pi. 34, f. 30-34, (1882), rare in the 
Lingulelasma bed (8) and the Triplecia bed (10) but common 
in the Leptrena and Orthis beds (13, 14). It is often com- 
pressed and is probably R. perUt/niellosa Whitf., in the upper 
Maquoketa. 
7. Rhynchonella anticostiensls Billings, Pal. Foss., vol. 1 p. 
142. f. 119 a-c, (1862); Winchell & Schucfeert, Final rep. 
Geol. Sur. Minn.,vol. 3, pt. 1, p. 464, f. 34 a-c(1893) ; found in 
the Orthis bed (14) in Iowa, Illinois and Wisconsin. 
8. Rhynchonella neenah Whitfield, Geol. Wis., vol. 4, p. 
265, pi. 12, f. 19-22 (1882) ; is said to be found with the last 
named in Wisconsin and Illinois. 
10. Rhynchonella perlamellosa Whitf., loc. cit., p. 265, pi. 
12, f. 23-25; is very similar to tlie R. capax (Con.), and is re- 
ported from the same horizon in Wisconsin. 
The earliest of the above cited species is 7?. minnesotensia 
which in the Buff limestone bed (1) is found in schools filling 
whole lamina?, but the same are nearly all- small, globose and 
resemble the figures of R. orletilalin Billings, with which 
species tliey may be identical. Exceptionally a larger sized 
one is found that is a typical R. minnesotensis but the same 
is connected by every gradation to the smallest. Graduallj'^ 
the average size increases towards the top of the Stictopora 
bed (4) where the species disappears, but even there, although 
rarely, a specimen of the smnll form occurs. Typically the 
plications number about 20 on the ventral valve, of which 
tliree fall in tlie median sinus but often four or five rarely 
