504 CYPRAHAD A. 
auctorum), in which we see the smooth, thin, fragile, slender 
and fusiform varieties shadowing gradually to their various 
forms, from the thick, heavy, strong, ridged, undated, varicose 
typical Murex undatus. The series I speak of are the identical 
shells of Professor William King, which have passed into my 
hands, and were the illustrations of his valuable malacological 
paper in the 18th volume, p. 248, of the ‘Annals of Natural 
History,’ the perusal of which I earnestly recommend to 
naturalists, as he has therein demonstrated that in this species 
the singular and great deviations of form, as the slenderness, 
tumidity, markings, &c., do not arise from generic distinction, 
but from the influences of climate, habitat, food, and bathy- 
metrical considerations. 
If these views are valid, they explode the long-held opinion 
that external form and markings ought to be regarded as un- 
erring elements of generic distinction; and our observations 
appear sufficiently to prove that this doctrine has too long been 
insisted on, even in animals of essentially similar structure, 
both of the external soft parts and internal anatomy. 
CYPRAADA. 
The British species of this family are distributed in Cyprea, 
Marginella, and Ovula, which form part of Lamarck’s Colu- 
mellaride and Convolutide. Marginella is not entirely rolled 
on itself, as it has a short exserted spire. The canals at the 
base of the aperture of these genera are little more than 
emarginations. Many years since we examined the animals 
of Marginella and Ovula, but the notes have nearly escaped 
our memory, except that they are undoubtedly deposited cor- 
rectly as members of the Cypreade. The last two species 
were obtained im the corallme zone at Exmouth twenty 
years ago, the Ovula patula even plentifully, but my dredger 
has not taken a live specimen of either for many years. The 
animals are of the Muricidal type, and the chief peculiarity 
that the last-formed volution of the shell envelopes its 
1S, 
