472 



ZOOPHYTES. 



queutly to be seen. Very little is kiiowu about the reproduc- 

 tion of this animal ; and until the mode in which it performs 

 that important function shall have been made out, and it shall 

 have also been determined whether it passes through any other 

 phase of existence, we are scarcely in a position to speak posi- 

 tively of its true affinities. The nature of its luminosity is 

 found by microscopic examination to be very peculiar ; for what 

 appears to the eye to be a uniform glow, is resolvable under a 

 sufficient magnifying power into a multitude of evanescent 

 scintillations ; and these are given forth with increased intensity, 

 whenever the body of the animal receives any mechanical 

 shock, such as that produced by shaking the vessel or pouring 

 out its contents, or is acted on by various chemical stimuli, such 

 as dilute acids, which, however, speedily exhaust the light-pro- 

 ducing power, occasioning disorganization of the body. 



309. Anthozoa. — This group, which constitutes the second 

 great division of the class of Zoophytes, includes all those larger 

 forms, whose polypes, when expanded, present the likeness of 

 "animal flowers:" and it consists of two principal subdivisions, — 

 the Asteroida, or Alcyonian zoophytes, whose polypes, having 

 only six or eight broad short tentacula, present a star-like aspect 

 when expanded, — and the Helianthoida, whose polypes, having 

 numerous tentacula disposed in several rows, bear a resemblance 

 to sun-flowers or other composite blossoms. Of the first of these 

 orders, which contains no solitary species, a characteristic ex- 

 ample is found in the Alcyonium digitatum of our coasts, which 

 is commonly known under the name of " dead-man's toes," or 



Fig. 230. 



Fig. 231. 



Fig. 232. 



'"sii^ 





=^@; 



230. Spicules of Akyrmiam and Gorgania. Fia. 231. Spicules o( Gorgonia guttata. Fig. 232. Spicules 



of Muricea elongata. 



" sea-paps." When a specimen of this is first torn from the rock 

 to which it has attached itself, it contracts into an unshapely 

 mass, whose surface presents nothing but a series of slight de- 

 pressions arranged with a certain regularity. But after being 



