SPONGES, GRAPTOLITES, CORALS. 57 
Receptaculites oweni.] 
diameter of this species is from four to twelve inches, and nearly every specimen 
obtained preserves the nucleus, Fragments are rare, but when secured prove 
to be portions not far removed from the nucleus. If &. oweni were originally a 
spherical or pyriform body, we should expect to find fragments of the upper 
portion, and these could be readily determined by the impression left by the 
head-plates. Such parts have not been discovered in the Northwest. Further, 
it is stated that “the genus /schadites agrees essentially with Receptaculites in 
structure, but its skeletal elements are more slender.’ We fail to find an in- 
ternal integument in Jschadites, or the lateral extension of the vertical rays in the 
“oastral” cavity ; they have been observed as terminating freely, and pointed at 
their extremities, in specimens of Ischadites iowensis, but apparently end bluntly in 
Lepidolites. It may be that the lateral extension of the vertical rays of the spicules 
forming the upper integument in R. occidentalis and R. oweni served the same purpose 
as the large number of plates discovered by Herr Rauff, closing the heretofore sup- 
posed apical opening in Ischadites, 7. e. for the regulation of the water currents. These 
lateral extensions of the vertical rays of the upper surface in F. oweni are traversed 
by from ten to twelve horizontal canals. 
ReEcEPrACULITES OweENI Hall. 
PLATE Ff, FIGS. 1-4. 
1844. Coscinopora sulcata OWEN (non Goldfuss). Geological Report of lowa, Wisconsin, and Illinois, 
p. 40, pl. 7, fig. 5. 
1861. Receptaculites oweni HALL. Report of the Superintendent of the Geological Survey of Wiscon- 
sin, p. 13. 
1862. Receptaculites oweni HALL. Geological Report of Wisconsin, p. 46, fig. 2, and p. 429. 
i868. Receptaculites owenti MEEK and WORTHEN. Geological Survey of Illinois, vol. iii, p. 302, pl. 2, fig. 3. 
1882. Keceptaculites owent WHITFIELD. Geology of Wisconsin, vol. iv, p. 239, pl. 10, fig. 7. 
1883. Receptaculites owenti HALL. Twelfth Rep. State Geologist of Indiana, p. 243, pl. 1, fig. 1. 
1884. Receptaculites occidentalis (partim) HrNDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 842. 
Original description —* Body consisting of a broad expanded disc, from four to 
twelve inches [even twenty inches] in width, and from one quarter to half an inch 
[sometimes 20 mm.] in thickness (rarely a little thicker). Surface undulating with an 
abrupt funnel-shaped depression in the center of the upper side | with a small conical 
projection on the under side], from which the cell rows [head-plates of the spicules] 
radiate in curved lines. 
“The thickness in the center is not more than one-eighth of an inch, and at a 
distance of three or four inches from the center is less than half an inch: cells [ver- 
tical rays of the spicules] cylindrical in the middle and contracted both above and 
below [from 1 to 3 mm. in diameter], the walls of the cavities often showing trans- 
verse striz, which appear like the remains of septa [since these cavities are casts of 
