CRUSTACEANS. 149 



portion of the brood is reserved for tlie adult state, the obstacles are so 

 numerous to its attainment. Could we preserve them, very few would 

 suffice for all our wants : they would elucidate all our doubts. 



None but li\dng subjects occupy a place in these volumes. Indepen- 

 dently of my invincible repugnance to injure or destroy, it is self-evident 

 that destruction immediately counteracts the object proposed, namely, 

 what animated beings shall do. K we hope to render our acquaintance 

 with them useful, they are to be always beheld in the most vigorous 

 condition. We cannot otherwise discover their form unimpaired, their 

 motions unembarrassed, the quahty of their food, their mode of perpe- 

 tuation, and their peculiar habits. 



It is an absolute error, believing that, with the loss of Ufe, such 

 animals as are sheltered by a hard integument, undergo no alteration. 



The preferable method of counterbalancing the evils inseparable 

 from destruction, is obtaining multiplied correct delineation of the whole 

 animal frame, and of many of its complicated parts. Thus may the or- 

 ganic structure be explained and understood. 



This, however, may seem a very wide prospect ; — of distant comple- 

 tion, and demanding the work of various hands, as guided by various 

 principles. 



The habits of the Crustaceans are extremely diversified, according 

 to the different genera, comprising such a comprehensive class of animals. 

 Some are aU life and activity ; others can be scarcely seen to move. 

 Some subsist on Uving animals. Burying their external organs in the 

 flesh, it is not known that they ever abandon the position once assumed. 



Perhaps as animals of prey many of the Crustaceans are solitary, for 

 very few such are known to hunt in concert. But several dwell in 

 numerous societies. Also some are said to be gregarious : and, although 

 not in Scotland, that they accumulate in quantities compared to hillocks 

 in other countries. Possibly this may be in the cold season. 



Notwithstanding their delicate nature, perhaps the life of a few in- 

 dividuals escaping the pursuit of enemies and the war of extermination 

 is long. 



It is one peculiarity of certain species, that they simulate death, lying 



