birds' nests. 127 



in the higher class vertebrata. A singular power that the Crustacea possess 

 must not be omitted; they can break off their own limbs at pleasure, which, 

 as the author observes, "is an indispensable provision in their economy," 

 for, as their blood flows in wide sinuses, instead of being confined in narrow 

 veins, if a limb happened to be fractured, the blood would inevitably escape, 

 the Crab therefore breaks off the injured member at a particular place where 

 one of these sinuses ends, and the bleeding is thus effectually staunched. 

 But the most remarkable thing is, that when broken off, notwithstanding 

 the high organization of these creatures, another limb gradually appears in 

 its place. 



The eyes of crustaceans are either simple, aggregated, or compound. 

 The first resemble those of Spiders; the second are composed of a number 

 of simple eyes placed behind one common cornea; and the compound are 

 constructed like those of insects. In the two highest orders these organs 

 are placed on moveable pedicles. They possess a distinct auditory apparatus 

 of a very simple character. In their generative system they are very 

 peculiar, these organs on each side of the body of both male and female 

 being perfectly distinct both internally and externally. The females almost 

 invariably carry their eggs about with them till they are hatched; and 

 for this purpose some of the minute Crustacea and Entomostraca have little 

 bags attached to the hinder part of their bodies, while the Decapods carry 

 their eggs attached to the under part of their tails. These Entomostraca 

 resemble the Aphides in one very peculiar fact — they are capable of pro- 

 ducing, from a single intercourse, fertile eggs for at least six generations. 

 The young of the Crustacea are not like their parents when hatched, but 

 undergo a sort of metamorphosis, like the insect world we have already 

 considered; and the Common Crab appears at first in the most grotesque 

 shape, and takes several months before it arrives at its perfect form. 



Uppinghaihj March, 1857. 



BIRDS' NESTS. 



BY 0. S. ROUND, ESQ. 



In my former papers upon the habits, instincts, and formation of birds, 

 I have endeavoured to trace the use, ornament, and pleasure which the 

 system of creation receives from their preseuce. What a beautiful and 

 interesting class of beings they are, and how much they deserve the con- 

 sideration of those who take a delight in contemplating the wonderful 

 works of nature! I will proceed now to speak of that peculiar feature in 

 their instincts, which is only observed in very few animals beside, and 



