Lign. 104. Echinites from the Chalk. Lewes.
| Fig. | 1.— | Galerites albo-galerus: nat. |
| 1a.— | Base of the same, with the five teeth. | |
| 2.— | Ananchytes ovatus: 1/2 nat. | |
| 2a.— | Base of the same. |
Lign. 105. Holectypus (Galerites) inflatus.
Kimmeridge Clay, Switzerland.
The left-hand figure shows the summit; the middle figure a profile; and the right hand, a view of the base, with the mouth in the centre, and the outlet towards the margin. (M. Agassiz).
Holectypus (Galerites) inflatus. [Lign. 105.]—In certain kinds of Galerites, the shell is strengthened internally by five strong ribs or projections, which of course leave corresponding deep furrows or channels on the flint casts moulded in them; such fossils are not numerous on the ploughed lands of the South Downs. These echinites are placed by M. Desor in the genus of which an example is figured in [Lign. 105].
The shell is hemispherical, and circular; the base flat; the tubercles are disposed in series; the inside of the case is supported by ribs.
DISCOIDEA CASTANEA.
Discoidea (Galerites) castanea. [Lign. 106.]—The Galeritidæ, which have a polygonal mouth, with the tubercles disposed in vertical rows from the summit to the centre of the base, as in the Cidarites, instead of being uniformly spread over the surface, as in G. albo-galerus, are placed in the genus Discoidea, by M. Agassiz.