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^ater, doubtless 
become fixed and converted into polyps. 
Atractylis arenosa, 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 piimila, 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 MoUusca, the Annelidge, the Insecta, and even 
amongst the Vertebrata, as in the common frog. We may 
ask, How is it that the ova of Hydractinia and Coryne are 
discharged into the w^ater to float about without any pro- 
tection, while those of Atractylis arenosa, the Sertularias 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. Eeproduction 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 
