292 On the Murex Corona. 



do not show through the substance of the shell. The right 

 lip slopes gradually to the end of the beak. The spire re- 

 sembles a spiral staircase formed of undulated, imbricated, 

 membranaceous scales, which rise into arched spines on the 

 angle of the whirls. This rare and beautiful shell was lately 

 brought from its proper habitat in the Gulf of Mexico. Dill- 

 wyn had never seen it, and Lamarck calls it very rare. This 

 specimen is much larger than any hitherto known to be de- 

 scribed. The back of the shell has very much the appear- 

 ance of the Murex melongena, but the flat channeled, coro- 

 nate, plaited spire, renders it remarkably distinct from any 

 other known species. The plates on the spire serve to 

 mark the lines of growth, or periods of spontaneous enlarge- 

 ment ; and they may be counted to more than one hundred, 

 before they become indistinct on the point of the spire. 

 These periods of increase have never, to my knowledge, been 

 observed ; but from what we see in analogous cases, we may 

 perhaps conjecture that they are annual. If so, the specimen 

 before us has weathered the storms of more than a hundred 

 years unhurt, amidst the ceaseless chafing of the tides and 

 tradewinds. 



P. S. There is reason to believe that the Natica patula of 

 Sowerby, as mentioned in vol. I. p. 13G, properly belongs to 

 the genus Sigaretus, as some very similar shells have lately 

 been found entirely enveloped by the animal ; of which, in- 

 cluding several new species, a full account may be given 

 hereafter. 



