78 



ANTHOZOA. 



Fig. 37. 



to those exhibited in the annexed diagrams (fig. 37), intended to 

 illustrate the manner in which the morphological changes are brought 

 about and the several special or- 

 gans of the Actinia unfolded. The 

 figures may be thus explained : 



1. Outline of the mature embryo- 

 nic corpuscle after the disappear- 

 ance of the cilia with which, at 

 an earlier stage, it is furnished. 



2, 3, 4. Primary involution of the 

 integumentary membrane. 5, 6. 

 Re-induplication of the external 

 membrane and formation of a 



stomachal cavity. In the two latter figures may likewise be seen the 

 commencement of the tentacula (a) and ovarian septa (6), which are 

 all formed by the same process of involution*. 



(173.) The perigastric spaces of the Actiniae enclose, in addition to the 

 reproductive apparatus, abundant convolutions of very remarkable fili- 

 form organs of great length and tenuity (fig. 38), concerning the nature of 

 which much diversity of opinion still exists. These convoluted threads 

 have, in fact, no communication whatever with the generative organs ; 

 they seem to consist of long, semi-capillary csecal tubes, attached by a 

 short mesentery to the lower margin of the perigastric septa ; and from 



Fig. 38. 



Convoluted filiform organs of Actinia. 



each of them a cord, slightly larger than the filament from which it is 



* " Observations on the Anatomy of Actinia," by T. Spencer Cobbokl, M.D., Annals 

 of Nat. Hist., Feb. 1853. 



