POLYPI. 177 



CHAPTER X. 



ZOOPHYTA. 



I PROPOSE to take up next the group of Zodphyta, of which 

 the Sea-anemones, (fig. 28, p. 57,) Corals, Hydras, (fig. 27, p. 55,) 

 Jelly-fishes, (fig. 37, p. 70,) Starfishes, (figs. 109, 110,) Trepangs, 

 (fig. 54, p. 120,) and the like, are there presentatives. This is 

 a type of organization in which the various organs repeat 

 themselves, more or less, between the back and the abdominal 

 mid-line of the body ; that is to say, they are laterally repetetive 

 on each side of an imaginary plane which divides the body ex- 

 actly into right and left halves. Whether the repetitions are few 

 or many, they always have reference to the two halves of the 

 body. This multiplication of parts I have already pointed out 

 in the organization of the Sea-anemone, (pp. 57, 58, figs. 28, 29,) 

 showing that its semi-partitions, as it were, split the body length- 

 wise into so many galleries. I will not repeat what I have 

 already said in regard to this animal, but will add a few words 

 in reference to the mode of proceeding which is adopted when 

 the parts of the organization are multiplied as the individual 

 increases in age. Exteriorly this is most conspicuous in the 

 development of the feelers or tentacles. As I have already said, 

 (p. 59,) the young begins with six double semi-partitions, which 

 correspond in position to the first six tentacles ; but what I will 

 point out here is, that the tentacles always agree with the num- 

 ber of the pairs of the partitions, not only in the young but also 

 in the largest individuals, where these feelers may be counted by 

 hundreds. 



At first the young Anemone develops the primary set of ten- 

 tacles, (figs. 106, 107, I,) and then the semi-partitions (/?, p 1 ) 

 appear next, and in such a position as to seem to be inward 



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