134 



ACTINOZOA. 



in radii, along the base and disc. Their arrange- 

 ment is best seen in living, semi-transparent 



without 



are 



mesenteries 

 munication 



Thus, a number of imperfect chambers 

 formed, all opening into one another below or 

 beyond the free edges of the mesenteries ; and, in 

 some cases, apertures occur in the sides of the 



themselves by which a further corn- 

 is kept up. These apertures usually 

 appear in the midst of the wide upper portion of 

 the mesentery, not far from the under surface of 

 the disc. They are most constant in the primary 

 partitions ; the secondary mesenteries being fre- 

 quently imperforate. The tentacles, which are 

 hollow, and, in many Actiniae, perforate at their 

 free extremities, open directly into the somatic 

 chambers. 



To the faces of the mesenteries are attached 

 the reproductive organs, which occur as thickened 

 bands of a reddish tint, containing ova or sper- 

 matozoa. The male and female organs appear 

 perfectly similar, previous to examination of their 



contents. 



dioecious 



external character can the individuals of both 

 sexes, which seem to be about equally numerous, 

 be distinguished from each other. Accurate obser- 

 vations are yet wanting on the reproduction of 

 Actima. It is probable that the spermatozoa, 

 first diffused in sea-water, find their way through 

 the mouth to the ova contained in the general 

 cavity of the body. 



> A long convoluted cord, or < craspedum,' arises 

 in front of the reproductive apparatus, along the 

 free edge of each mesentery. In addition to the 

 craspeda, other organs of similar structure, termed 



