202 J. S. GARDNER ON BRITISH CRETACEOUS PATELLTD.E ETC.
width of the ribs. The scar, which is immediately under the apex, is very open, and is unsymmetrical.
The specimen is from the Upper Chalk of Kilcorrig, Lisburn, and is preserved in the Jermyn -street Museum.
Crepidtjla gaultina, Buvignier. Gault. PI. YII. figs. 21-23.
Shell small, thin, suborbicular, inflated and rounded, sometimes as high as wide, more frequently depressed ; smooth, without radiating lines, but with irregular folds of growth ; apex minute, posterior, in front of the septum, spiral, easily detached, marked with strong lines of growth. The scar seen on the casts is directly under the apex, and resembles a widely opened V, or, more cor- rectly, a distant bird in flight. The position of the septa can be traced externally on the shell itself by slight ridges. The fry was perfectly helicoid and finely ribbed.
It is found in the Gault of Folkestone, and at Cambridge, attached to shells of Ammonites, aud has been met with in the Gault of France and Switzerland.
It has been figured by Buvignier, in the, ' Stat, de la Meuse,' by Pictet and Campiche, and by Jukes-Browne (Quart. Journ. Geol. Soc, May 1875).
The depressed form only has been met with as yet at Folkestone ; but the amount of depression, depending entirely, as it does, on the position in which the shell, when living, was fixed, has no specific value. A larger series may unite the species with Calyptrcea Cook- sonice.
Crepidtjla alta, Seeley. Gault.
Shell smaller, and relatively higher than that of C. gaultina, with the septal scar less open.
This is the Galericulus alius of Seeley, a genus founded on a unique specimen in the Woodwardian Museum. The genus Galeri- culus is characterized, according to Seeley, by a second septum near the base of the shell. The scar considered to indicate this septum, however, is very much to the right of the median line, and, as already pointed out by Jukes-Browne, is probably an accidental indentation, as it is difficult to see the use of a second septum in the economy of the living mollusk, and nothing analogous exists in recent genera. The figure and description are in the ' Ann. and Mag. Nat. Hist.' for April, 1861. It may, probably, be only a variety of C. gaultina, and should, I think, be eventually removed from our list.
Crepiduxa cham^formis, sp. nov. Lower Greensand. PI. VII. figs. 12-14.
Unsymmetrical, capuliform, depressed ; apex posterior, recurved, spiral (?), projecting beyond the margin ; posterior region much excavated under the apex ; aperture irregular ; surface rugose, with lines of growth.
This shell is very like C. grandis, from Japan, and resembles a
