APPENDIX. NOTES. 405 



retire occasionally into it, like the above animal. With 

 regard to his second species, though some parts of his 

 description agree with the common jelly-fish, yet their 

 devouring Echini and Cockles seems to indicate some 

 animal furnished with a more powerful apparatus for 

 making their way to the animal inhabiting these shells. 

 Pliny does not in his description merely copy Aristotle ; 

 for he speaks of his sea-nettle as producing the same 

 effect as the vegetable nettle. Yet he mentions them and 

 the sponges as being something intermediate between the 

 animal and the plant, which can scarcely apply to our 

 Jelly-fish. It seems, I think, probable, that the term in 

 question was employed by the ancients, to designate more 

 than one group of animals, and more particularly the 

 Tunicaries of Lamarck, both those that are fixed and those 

 that are free. Aristotle's fixed species, which he describes 

 as retreating into the rocks, as into a shell, will probably 

 one day be found near the eastern coast of the Black Sea. 

 It is worth while also to inquire whether any animal 

 answering the description of Aristotle's second species is 

 still eaten, in the winter, by the Greeks, customs of that 

 kind seldom changing. 



NOTE 23, p. 240. It seems to me most probable that 

 they are the animals, and not the pholads, as is usually 

 supposed, which the Roman naturalist describes under the 

 name of Dactule. Pliny says of his Dactyli that they are 

 so called, because of their resemblance to the human nail; 1 

 in the Pholads this resemblance is very slight, but in the 

 rasor-shells and some tulip-shells it is much more striking. 

 He also observes that the Dactylus when replete with 

 moisture sparkles in the mouth of the eater, and that the 



i Hist. Nat. 1. ix. c. 61. 



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