TROCHUS. 315 
Solaria, that I shall only observe, at present, that figures 1, 2, 
41, 42, of Seba, and the exterior O of Gualtier, must, at the 
least, be excluded as representations. 
Crochus Hybrivus. 
Even before the publication of the ‘Museum Ulrice,’ that 
work was referred to for a more ample account of the T'rochus 
hybridus than was furnished by the bald outline of its characters 
in the ‘Systema.’ It is to the Dronningen Museum, then, and 
not to the private cabinet of our author, that we must look for 
the type of this species. The name was probably significative 
of its being a mongrel “ Staircase,” a link between perspectivus, 
of which Linneus appears to have almost deemed it a mere 
aberrant variety !, and the succeeding T'rochi. 
From the details of the ‘Museum Ulrice’ naturalists have 
identified the species with the Solariwn hybridwm (Chemn. 
Conch. Cab. pl. 173, f. 1702, 1703), which traditional recogni- 
tion, although the Mediterranean locality renders it not im- 
probable that the allied Sol. lutewm was the shell designed in 
the ‘Systema,’ it is not desirable to gainsay. Strictly speaking, 
“ bidentata”’ 1s not appropriate for either; the expression, how- 
ever, evidently refers to the extremities of the cord-like ridges 
that flank the columellar canal. 
Trochus crvuctatus. 
The value of the tedious analytical process of examining the 
entire contents of the Linnean cabinet, with a view of ascer- 
taining whether more than one shell suits the meagre descrip- 
tion published by our author, is here proved by the recognition 
of this hitherto uncertain species in a variety of the Monodonta 
Vielloti of Payraudeau, which precisely and exclusively agrees 
with the description and the stated locality. The white cross 
is formed, as indeed is suggested in the “ fasciis, &c.” of the 
definition, by the union of the pallid markings in four streaks 
that radiate from the apex; in fine specimens there are two 
