viii PREFACE. 



The suitable mode of preservation depends on the nature of the race. 

 But, after supplying their native element, first, the observer must guard 

 against those destructive propensities of many of the lower animals, 

 prompting them to wage war on each other. The Cnistncea and the 

 Actinia are fell devourers of whatever they can overpower. The Asterias, 

 and the Echinus, and some of the leeches, are ravenous of prey. But the 

 Holotliuria, the Amphitrite, TerebeUa, and the whole ascidian tribes, seem 

 perfectly harmless. 



The element wherein the captives are kept should be always recent, 

 generally pure, the vessels clean, and free of tainted matter. Some fall 

 immediate victims to putrescence ; others can resist it wonderfully, either 

 endeavouring to escape by ascent, or by descent, according to their pe- 

 culiar nature, or closing themselves up as if to avoid its deadly influence. 

 The water for most of the Crustacea should be free of mud, and contain 

 eminences whereon they may rest at will, above the surface. But muddy 

 solutions are essential to most of the bivalve Testacea, and to all the as- 

 cidian tribes, unless belonging to some of the foliaceous or other zoophytes. 

 Such solutions are grateful to certain Amphitrite, to many Vermes, as 

 sand is to various species of the Nereis. Capacious vessels are commonly 

 beneficial, and within them should be shells or stones for retreat and shel- 

 ter. The presence of the common Lepas of the shore, is useful as an in- 

 fallible guide, by its display, to the purity of the water. 



The naturalist's earliest care ought to be obtaining an accurate de- 

 lineation of his subject — always selecting the finest specimen — and taking 

 it in motion, or when the parts are best unfolded. Herein it is prefer- 

 able to employ another's talent than the naturalist himself, though a skil- 

 ful artist. Many delusions are ever ready to mislead, but of two observers, 

 each may correct the other. After delineation, the subject can be stu- 

 died at leisure. 



Respecting the representation itself, where indispensable to havefigures 

 larger than life, that is, as shewn by lenses and microscopes, nothing more 

 is requisite than what will favour distinct inspection. There, the author 

 and the artist should stop. We are now less removed from the reality. 

 Preservino- distinct vision, perhaps diminution will be preferable to 



