CONCLUDING CONSIDERATIONS. 335 



moderns tell us of the Nautilus of the sea, of the tiny 

 creature in its fairy shell-chariot, that, throwing out its 

 ballast, rises to the surface, and spreads its gauzy canvas 

 to the breeze, but when a storm comes, or danger 

 threatens, hastily assumes its ballast again, and sinks 

 in safety to its refuge at the bottom had all that been 

 true, there might have been, on the part of Dr. Erasmus, 

 another nut for his grandson to crack. But the Pinna 

 is quite as hard a nut ; and it is thus that the grand- 

 father, referring to Linnaeus, speaks of it : 



" The Pinna, or Sea-slug, is contained in a two - valve shell, 

 weighing sometimes fifteen pounds, and emits a beard of fine, long, 

 glossy, silk-like fibres, by which it is suspended to the rocks, 

 twenty or thirty feet beneath the surface of the sea. In this situa- 

 tion it is so successfully attacked by the light-footed Polypus" (a 

 Cuttle-fish, says a Cyclopaedia, that rushes upon her like a lion), 

 " that the species perhaps could not exist but for the exertions of the 

 Cancer pinnotheres, who lives in the same shell as a guard and 

 companion. The Pinnotheres or Pinnophylax is a small crab, naked 

 like Bernard the Hermit, but. is furnished with good eyes, and lives 

 in the same shell with the Pinna ; when they want food the Pinna 

 opens its shell, and sends its faithful ally to forage ; but if the 

 Cancer sees the Polypus, he returns suddenly to the arms of his 

 blind hostess, who, by closing the shell, avoids the fury of her 

 enemy ; otherwise, when it has procured a booty, it brings it to the 

 opening of the shell, where it is admitted, and they divide the prey." 



This is a story, evidently, that requires authentication ; 

 but it is strange that the latest Encyclopaedias scarcely 

 disturb it. 



However it be, it is a Darwin that speaks l ; as thus 

 also of the Sturgeon 



" His mouth is placed under the head, without teeth, like the 

 opening of a purse, which he has the power to push suddenly out 

 or retract. Before his mouth, under the beak or nose, hang four 



1 His reference to Linnaeus for the Pinna is, Syst. Nat. vol. i. pp. 

 11 59 and 1040. 



