Observations on British Zoophytes. 



351 



which still remains attached to the summit of the empty 

 generative sac (fig. 10 d). The ova now undergo fissure, 

 and are developed into planulse within their nest, then at 

 last escape, and, after swimming in the w T ateiy douhtless 

 become fixed and converted into polyps. 



Atractylis are?iosa, although it gives off an immense num- 

 ber of young, is one of the rarest zoophytes on our coast, 

 probably on account of the low viability of its planulse. 

 While Sertularia pumila, one of the commonest species, and 

 which produces its young in the same way, will quickly line 

 the vessel in which it is kept with forests of young zoo- 

 phytes, not a single planula of Atractylis arenosa, of the 

 immense number that were given off by my specimen, ever 

 attained the polyp stage. 



We have in this zoophyte the reappearance amongst the 

 Tubulariadse of a mode of gelatinous nidification, which ob- 

 tains in various orders of the animal kingdom, — in the Pro- 

 tozoa, the Mollusca, the Annelidae, the Insecta, and even 

 amongst the Yertebrata, as in the common frog. We may 

 ask, How is it that the ova of Hydractinia and Coryne are 

 discharged into the w r ater to float about without any pro- 

 tection, while those of Atractylis arenosa, the Sertitlarias and 

 Laomedias, require such various provisions for their protec- 

 tion ? but we do not find anything in the physiology of the 

 zoophyte to answer the question. 



2. Atractylis miniata. (New Species.) 



Polypary yellow dendritic, branches given off at an acute 

 angle from the stem, crooked, wrinkled but not ringed. 

 Polyp with eight alternate tentacles, buccal cavity 

 silvery, endodermal lining of stomach bright red-lead 

 coloured. Keproduction not observed. 

 This zoophyte was found on stones at Largo, in little 

 gnarled shrubby trees about an inch high, exposed at the 

 lowest tides. The bright yellow colour of the polypary 

 at once strikes the eye, which is also arrested by the 

 gaudy colour of the minute polyps. These appear to be 

 marked by two broad internal patches: one, correspond- 

 ing to the buccal cavity, of a dense silvery white ; the other 



VOL. II. 2 z 



