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20. The various bundles of fwimming fea 

 weeds ought not to be neglected ; for befides the 

 different kinds of fuci they confift of* they ge- 

 nerally contain fmall crabs, fhrimps, or other 

 fubmarine infects or worms, fuch as the onifci, 

 monoculi, fometimes fhells and efcharae, fertu- 

 lariae, and other corallines. 



21. The various animals inhabiting fhells de- 

 ferve inveftigation, as there are probably new- 

 genera yet to be difcovered : It is not fully 

 afcertained whether the inhabitant of the paper^ 

 nautilus be an animal really belonging to that 

 fhell, or only ufes it in the fame manner as 

 fome crabs do other fhells neither is it known 

 whether or no the paper-nautilus animal, or the 

 lepia, increafes or enlarges its fhell. Indeed 

 the generation, and general ceconomy of all the 

 mollufca clafs is very imperfectly known. 



22. Experiments might be tried to afcertain 

 whether pearls are not fuch concretions in the 

 fhells wherein they are found, as the crabflones 

 (Lapides feu oculi Cancrorum) in the fhells of 

 the river cray-fifli, which collect alkaline or 

 calcareous materials from the food of the animal 

 for the formation of the new fhell, as do the 

 Mya and Mytilus margaritifer a new layer for 

 the incfeafe of their fhells. Do the fhells con- 

 taining the pearls gradually increafe through 

 the year, or at a certain feafon only ? 



23. It mould be carefully remarked which of 

 the fhells, efpecially of the Murex and Turbo 

 kinds, afford a red or purple juice fit for ftain- 

 ing or dying like the purple of the ancients ; 

 whether the dye be permanent, and the method 

 of preparing and applying it by fome Indian 

 nations. D'UUoa, in his South- American voy- 

 age, 



