142 



THE HARMONIES OF NATURE. 



tissues. The vegetative organs are very much developed, and 

 generally disposed in a curve, so that the mouth is proximate to 

 the opposite extremity of the intestinal canal. From the crus- 

 taceans and insects they are distinguished by the absence 

 of jointed feet, from the fishes by the absence of an internal 

 skeleton and spinal marrow. A view of the various subdivi- 

 sions of this great class, proceeding from the lowest to the 

 highest types of mollusc organisation, will show us that, though 

 generally weak and inert, they are all most admirably fitted out 

 for the battle of life. 



While wandering on the beach we not seldom find, among the 

 relics of the retiring flood, pale-coloured leaf- like formations, 

 of a papery substance, which might be 

 mistaken for dried sea-weeds, blanched 

 by exposure to the air. But a narrower 

 inspection soon shows that the flustrae, or 

 sea-mats, as these marineproductions are 

 called, are of a much more complicated 

 structure than that of a simple alga, 

 as they are built up of innumerable little 

 oblong cells, placed back to back, like 



those of a honeycomb ; and each crowned (as may readily be 

 seen with the help of a pocket lens) by four stout spines. 



Before the stormy tide detached these foliaceous formations 

 from the bottom of the sea, and left them to perish on the shore, 

 each of these cells contained a living creature, whose mouth was 

 surrounded with a coronet of filiform and 

 ciliated tentacles, destined to produce a vortex 

 in the water, and thus to provide their tiny 

 owner with its food. The body was bent on 

 itself, somewhat like the letter V; the one 

 branch (a) being the mouth and throat, the 

 other (b) the rectum opening by an anus, 

 and the middle part (c) the stomach, probably 

 with some accessory organ. The tenant of 

 each cell, though enjoying an independent 

 existence, was linked at the same time by 

 a common circulation to the proprietors of 

 the cells above and below him, and thus the 

 whole formed a community of perhaps forty or fifty thousand 



Leaf-like Sea Mat. 



Flustra in its cell. 

 Highly magnified. 



