RECEPTACULITES. 139 
17. Recepracuiites Neprunt, Defrance. Plate II, fig. 3, and Plate IV, fig. 1. 
1827. Recepracunites Nepruni, Defrance. Dict. des Sciences Nat.,.vol. xlv, 
p- 5, Atlas, pl. lxviii, figs. 1 a, 16, 
Merl: 
1826-33. CoscINOPORA PLACENTA ET suLcATA, Goldfuss. Petref. Germ., Th. 1, 
p. 31, pl. xix, figs. 18, 19. 
1842. Recepracurrres Neprunt, Archiac and Verneuil. Trans. Geol. Soc., ser. ii, 
pt. 2, p. 407. 
1844. — — Ft. Roemer. Rhein. Uebergangsgeb., p. 59. 
1852. — = Quenstedt. Handb. d. Petref., p- 670, pl. 1x, 
fig. 18. 
1868. — — Dames. Zeitsch. d. deutsch. geol. Gesellsch., 
Bd. xx, p. 483, pl. x, fig. 1. 
1875. _ — Giimbel. Beitriige Abhandl. d. k. bay. Akad. 
der Wiss., Cl. ii, Bd. xii, Ab. 1, 
p- 169, pl. a. 
1878. — _ Quenstedt. Petref. Deutschl., Bd. v, p. 596, 
pl. 142, fig. 20. 
1878. — SCYPHIOIDES, Quenstedt. Idem., p. 586, p. 142, figs. 15, 16. 
1879. — Neprunt, Micholson. Man. Pal., vol. i, p. 127, fig. 29. 
1876-80. _— — Zittel. WHandb. d. Pal., p. 84, fig. 20. 
1880. — a= F. Roemer. Lethwa pal., vol. i, p. 290, Atlas, 
pl. xxxv, figs. 7 a, b, e. 
1882. os — T. R. Jones. Cat. Foss. Foram. Brit. Mus., 
p. 4. 
1884. — _- Hinde. Quart. Journ. Geol. Soe., vol. xl, p. 841. 
1885. — — Vosmaer. Porifera. Bronn’s Klassen u. Ord- 
nungen d. Thier-Reichs, Bd. ii, 
p- 275. 
Sponges varying in form from flattened dises with a circular outline, to open 
cups, and ranging from 65 to 180 mm. in diameter. The walls, as a rule, gradu- 
ally increase in thickness, from the conical nucleus, where they are about 3 mm. 
in thickness, towards the margin of the dise or cup, where they attain a thickness 
of 10 to 15 mm., and in one exceptional example 20 mm. 
The rhomboidal spicular plates of the outer or under surface of the Sponge- 
wall are usually flat, though in some specimens they become concave through 
pressure; their edges are thin and usually crenulated beneath. They vary from 
4 to 5°5 mm. in width. They are disposed so that a linear interspace exists 
between adjoining plates, which is shown by the curved decussating ridges in the 
casts of the outer surface. The transverse or horizontal spicular rays are conical, 
from 1 mm. to 1°5 in thickness; they usually extend beyond the respective head- 
