250 CRETACEOUS GASTROPODA 
Species, which have to be referred to Sodariwm, begin in the Trias,* and gradually increase to 
the tertiary period, when they seem to have reached their maximum of development ; for there are not 
more than 50 recent species known, and these live principally in tropical waters. 
Pictet, in his review of the cretaceous species of Solarium (Mat. Pal. Suisse, Foss. Ste. Croix. 3me. 
Ser., pp. 550-555)+ quotes forty species, among which, however, several alterations must be made. 
The surface of the shell, upon the ornamentation of which so many new species had been founded, 
is extremely variable in different stages of preservation. Still more doubt must be entertained about 
those species, which are determined merely from casts. In my revision of the Gosau-Gastropoda 
(Sitz. Akad., Wien, 1865, Vol. LIT, p. 61), I have noticed, that the three species, described by 
Zekeli as Sol. quadratum, d’Orbignyi, and textile, belong to the same species, formerly described by 
Sowerby as Sol. quadratum, Some similar alterations, we presume from this, may be expected among 
other known species. 
Binkhorst described from the Maestricht-chalk since the publication of Pictet’s list (Gast. et 
Ceph. craie., Limbg., 1861, p. 87, pl. 3, figs. 11 and 12) Sod. cordatum and (ibid. p. 77, p. 5°°, 
fig. 10) Sol. Kunraedtense. The first is a true Solarium, but the second could only be retained, 
if the shell were not pearly within, otherwise it more resembles JMargaritedla, and other 
Trocutpm, Baily describes (Ann. Mag., 1860, Vol. VI, p. 28, pl. 1, fig. 2,) a very fine species 
from the Upper Greensand near Dorchester under the name of §. Binghami. Guembel (Geog. 
Beschreibe. d. Bayer. Alpengeb., 1861, p. 578) named a species So/. ste//atum. Another species was 
lately figured by Guéranger as So/. Michelini, (Album pal. de la Sarthe, 1867, pl. 10, fig. 21), 
previously named in his ‘ Essay, etc.,’ 1853. 
Two species have been described from Africa, namely, So/. Bailyi, Gabb (Am. Phil. Soc., 1861, 
Vol. VIII, p. 95—So/. pulchellum, Baily, Quart. Journ. Geol. Soc., Lond., 1855, XI, p. 457, pl. 12, 
fig. 8, non idem d’Orbigny), and Sol. Vattoni, Coquand (Géol. et Paléont., Prov. Const., 1862, 
p- 182, pl. 4, figs. 7-9). 
To the American So/. Abyssine, Gabb, the same author lately added in the Pal. of California 1864, 
Vol. I, p. 116, ete., four species, under the generic name of Architectonica, namely, Sol. Veatchit, cog- 
natum, Hornii, and inornatum. The Sol. fleeui-striatum, BK. and Shum. (Meek and Hayden) forms the 
type of the genus Muargaritella and belongs to the Trocu1p#, because it has the internal shell pearly. 
From India a species of TrocHiD® was described by d’Orbigny (Pal. Astrol. pl. 4, figs. 9-11) as 
Sol. deperditum, which must be again excluded, but in its place we shall describe four new species, 
Sol. Arcotense, Kurribiemse, Coothoorense, and Vylapaudense, which all belong to the uppermost beds 
of our cretaceous deposits ; the two last-named species being rather common shells. 
1e. Solariorbis.—I find this name in Conrad’s Check lists of eocene and oligo- 
cene fossils, p. 13-14. There are four species mentioned, three of which were 
described by Lea in his contributions to Geology as Delphinula, Planaria, and 
Turbo. 1 really do not understand what the distinctive characters{ of the genus 
may be, for Lea’s determinations do not seem to be in the least contradictory to 
his figures, and rather detailed descriptions. 
2. Discohelix, Dunker, 1848, (Orbis, Lea§ not Lacp., Blain. a. 0.; Omalazis, 
apud H. and A. Adams and Gray; Bifrontia, apud Chenu). This genus was 
* Lanbe in Sitzgb. Akad., Wien, 1866, Vol. LIII, Fauna der Schichten von St. Cassian, etc., quotes a 
Solarium planwm. 
+ See also Gabbs’ Catalogue of cret. fossils in Proc. Am. Phil. Soc., 1861, VIII, p. 136. 
+ Conrad refers for the characteristics of the new species to the first Vol. of Am. Journal of Conchology, 
which we have not yet been able to obtain. 
§ Lea Contributions to Geol., 1833, p. 123, pl. 4., fig. 112. 
