362 CRETACEOUS GASTROPODA 
Species of Gibdula are very common in cretaceous deposits. Imay mention Zroch. Requienianus, 
VOrb., Turbo Goupilianus, VOrb., Turbo Brunneri, T. Coquandi, T. Viteli, Trochus Desori, 
P. Couloni of Pictet and Campiche (see Mat. p. 1. Pal. Suisse, 3me. Ser.), Turbo arenosus, Sow. 
(Sitz. Akad., Wien, LII, p. 534), Turbo inflerus, scaliformis, Herklotsi, granuloso-clathratus and 
Zekelit of Binkhorst, all belonging to the same type, as do Turbo Strombecki, rimosus, granulose-cinctus, 
clathratus, rudis, filogranus, cariniferus of the same author (Monographie Gast. et. Ceph. craie de 
Limbourg, 1861). It would not be surprising if all the last named forms from Maestricht were 
proved to belong only to one or two really distinct species, in one of which the spiral strie are more 
equal and almost smooth, in the other granulated and alternately thicker and thinner. 
Seeley describes from the Cambridge Greensand (Ann. Mag. Nat. Hist., 1861, VII, p. 290, 
pl. 11, fig. 16) a Tr. devistriatus, which he provisionally refers to Giddula. The shell of this species 
is rather thin, depressed, broadly conical, the whorls are squarish and spirally striated, base umbi- 
licated. It seems very probable that a new generic name must be proposed for this shell, if it does 
not belong to Margarita. I have described another species of the very same type from the Alpine 
Lias, Trochus rotulus, and also noticed the characteristic form and thin structure of the shell (Sitz. 
Akad., Wien, 1861, XLIII, p. 178, pl. 2, fig. 7). 
I shall note two new species, G2b. Jerdoniana and granulosa, from the South Indian cretaceous 
rocks. 
2. Diloma, Philippi, 1845. Shell conically depressed, like Gibbula, smooth or 
spirally striated; the umbilical region is covered with a thin, porcellanous expansion 
of the columella, forming an elevated ridge on the inner side of the labrum, but not 
uniting with the same (H. and A. Adams’ Gen. I, p. 419, Philippi, Handbuch, 1853, 
p. 209). 
3. Oxytele, Philippi, 1847, only differs from the last genus in having the 
-porcellanous expansion thin and gradually uniting with the labrum; the type is 
Trochus merula, Chem. 
A characteristic species occurs in our cretaceous rocks of South India, Ox. notabilis, which is the 
only cretaceous form fairly to be placed in this genus. There are, however, from the jurassic deposits 
a large number of species known (like Zroch. Belus, Acmon, Halesus, Pollux, Diomedes, Labadyei, 
described by D’Orbigny in his Pal. frangaise, ter. jur. vol. IL; Zroch. obsoletus, Morris and Lycett, 
and others, which most probably ought to be referred to the present genus, or partially to Diloma. 
The recent species of Diloma chiefly inhabit South America and Australia ; those of Ozyte/e, 
the Mediterranean and eastern seas. 
4. Monilea, Swainson, 1840, is characterized by a large umbilicus surrounded 
with a striated or undulated callus ; the inner lip is indented, having two or three 
small tubercles, in which the internal striz of the umbilicus terminate; the shell 
itself is rather solid. 
Several jurassic species appear to belong to Monilea, like Turbo Calypso and Eudoxus of 
d@Orbigny and others, but I am not acquainted with any from cretaceous rocks. 
H. and A. Adams (Gen. I, p. 481) consider Solariella, S. Wood, as a sub- 
genus of Monilea, but I rather think that it is more closely allied to Margarita, 
and shall notice it subsequently. 
5. Clanculus, Montfort, 1810 (H. and A. Adams, Gen. I, p. 415). 
6. Monodonta, Lamarck, 1799 (ibid. p. 417; Labio, in Philippi’s Handb., 
p. 209). There have been a few cretaceous and jurassic species described under 
the last named genus, but I do not think correctly, as none of them show an 
