20 



INTRODUCTION TO ZOOLOGY. 



instantaneous flash— a peculiarity alluded to by Crabbe, with 



his usual minute accuracy : — 



'' See, as they float along, th' entangled weeds 

 Slowly approach upborne on bladdery beads : 

 Wait till they land, and you shall then behold 

 The fiery sparks those tangled fronds unfold — 

 Myriads of living points; th' unaided eye 

 Can but the fire, and not the form, descry." 



Order IL— ASTEROIDA. 



" We'll dive where the gardens of coral lie darklina:. 

 And plant all the rosiest stems at thy head." — Moore. 



The animals of the ju-esent order are all marine. They are 



never found singly, but in a com- 

 munity, forming altogether a polype- 

 mass, variable in foim, strengthened 

 in different ways, and having on its 

 surface the cells in which the polypes 

 live, and which open on the surface 

 in a star-like figure, whence the order 

 takes its name {Fig. 10). 



To this order belong the family of 

 Pennatulidae, or Sea-pens. One 

 species, taken in abundance on some 

 parts of the Irish coast, is the Vir- 

 gularia mirabilis, a name which 

 denotes the beauty and singulai'ity of 

 its appearance, for it literally means 

 " wonderful little rod." It is dredged 

 from a muddy bottom, in water a 

 few fathoms deep, and comes up so 

 perfectly clean, that fishermen sup- 

 pose it stands erect at the bottom, 

 with one extremity fixed in the mud. 

 From the summit to the base of the 

 Virgularia runs a long white, cal- 

 careous substance — an axis imiform 

 ill thickness throughout. This is the 

 first instance Avhich has as yet come 

 before us of an animal possessing 

 the power of secreting calcareous 



10.— ASiEROID Poi.Yl'ES. 



