SPONGES, GRATOLITES, CORALS. 59 
Receptaculites owenl.] x 
are indicated by furrows left between the casts now filling the original spaces. 
Between the four principal canals, which seem to have communicated with four 
circular hollows, one situated at each angle of the rhombic spaces, are two other 
canals, and these also seem to have had openings in the upper surface. In other 
words, each plate had originally twelve small semicircular hollows communicating 
with twelve horizontal canals joining in the center with the vertical ray. Where 
the filling of the spaces between the canals is not preserved, tubercles can be seen 
distinetly situated at each angle of the rhombic depressions, with two, and occa- 
sionally only one pustule between them. Along their edges the plates are separated 
from adjoining ones by distinct walls. These walls are not a portion of the skeleton, 
but are foreign matter which has accumulated between the plates, and has more or 
less disturbed their natural position. 
This species is known throughout the Northwest as the “sunflower coral,” “lead 
fossil,” or Receptaculites owent Hall. The specimens from Minnesota are from lime- 
stone and calcareous mud-stones, and rarely occur as hollow casts, but commonly as 
impressions of the skeleton. The vertical rays are filled usually with crystalline 
calcite. 
Dr. Hinde, in treating of R. occidentalis Salter, and R. oweni Hall, says: “The 
examples from Illinois and other western states are usually of somewhat greater 
diameter than those from the same horizon in Canada, but from a comparison 
of specimens from these different places I am unable to detect any differences which 
would justify regarding them as distinct species. Their external aspect is, however, 
strikingly dissimilar owing to their different states of fossilization” (Joc. cit. p. 848). 
On account of the greater size attained by R. oweni, and the plates of the inner sur- 
face having twelve canals instead of four, as in R. occidentalis, a central knob on each 
head-plate of the spicules on the outer surface of the former, should be sufficient to 
distinguish this species. 
Formation and locality.—Throughout the Galena of Minnesota, Wisconsin, Iowa and Illinois. Some 
of the more prominent localities are: six miles south of Cannon Falls, Kenyon, Mineola, Fountain, near 
Marion, Wasioja, and Stewartsville, Minnesota; Decorah and Dubuque, Iowa; Green Bay, Wisconsin ; 
Galena and Dixon, Illinois. 
Collectors.—Miss Cora BE. Goode, W. H. Scofield, and the writers 
Mus, Reg. Nos. 3375, 4944, 6758, 7251, 7714-7721. 
SYNOPSIS OF AMERICAN SPECIES OF RECEPTACULITES. 
k. AROTICUS Etheridge. 
1878. Receptaculites arcticus EYMERIDGE. Quart. Jour. Geol. Soc. London, vol. xxiv, p. 576. 
1882. Keceptaculites arcticus JONES. Catalogue Foss. Foram. British Museum, p.°3. 
1884. Receptaculites arcticus HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 845. 
Formation and locality.—Lower Silurian ; Cape Louis Napoleon and Cape Frazer, Arctic regions. 
