504 



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. 



CYPE^BAD^B. 



The British species of this family are distributed in Cyprcea, 

 Marginella, and Ovula, which form part of Lamarck's Colu- 

 mellaridce and Convolulidte. 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 CypTGoda, The last two species 

 were obtained in the coralline 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 

 is, that the last-formed volution of the shell envelopes its 



