3G6 Mr. A. H. Hassall's Catalogue of Irish Zoophytes. 



believe, been fully understood : it is notbing more than faecal matter 

 kept in constant rotation by the action of the cilia lining the whole 

 internal surface of the alimentary canal, and which, by their pecu- 

 liar arrangement, drive it on towards the place by which it is to 

 make its exit — thus supplying the office of proper propelling mus- 

 cles. The polypi are usually non-symmetrical, one side being more 

 bulged out than the other, but they are capable of assuming various 

 other forms and appearances. The tentacula, too, vary much in 

 their disposition, being sometimes directed either outwards or ujj- 

 "wards ; at others they are curved inwards, usually to a small ex- 

 tent, but occasionally so much so as to be entirely lost to view, 

 being concealed by the outer tunic of the polypus. The motions 

 of the polypi of this species are very lively and peculiar. All the 

 Ascidian zoophytes are much more vivacious and active in their 

 movements than the Hydroid, and this is the necessary result of 

 their higher organization. " The stems, though commonly still, 

 have free power of motion ; and when one is disturbed it bends 

 quickly to and fro, so as to strike one or two more ; these again 

 strike upon others, and thus for a few seconds all are in action; but 

 they soon return to quietness, and the arms, which during the com- 

 motion had been doubled up, open again." — Lister. 



I much regret that I was unable, from want of time, to carry my 

 observations further on the anatomy of this species, so well adapted, 

 both from its size and the circumstance of its being the only known 

 naked Ascidian zoophyte, for anatomical examination. I have sent 

 a more perfect figure than has yet been given of this species to Dr. 

 Johnston. 



On Vesicularia spinosa : very rare : Dublin Bay. 



Crista acideata. Milne Edwards has figured this species, which 

 I described in the ' Annals of Natural History ' for November 1 840, 

 in the ' Annales des Sciences Naturelles ' for April 1S38, under the 

 name of La Crisie ivoire. How Milne Edwards could have con- 

 founded this somewhat rare species with the common one C. eburnea, 

 I am at a loss to conceive. Upon this latter species in no case have 

 I ever met with spines ; and had they ever existed, traces of them 

 would have been visible on the sides of the cells, as they always 

 are in C. aculeata, even when the teeth themselves have been broken 

 offi 



Rarely found on stones, east of Kingstown harbour. 



Hippothoa lanceolata. See Plate VIII. fig. 5, 6, for a representa- 

 tion of this elegant species. 



Trawled up oflf Bray on old valves of Pecten communis. 



Anguinaria spatulata. On stones east of Kingstown harbour, 

 abundant ; also at the Giant's Causeway, on Fuci. 



Tubulipora verrucaria, Milne Edwards. This sjiecies in its per- 

 fect state, as it occurs in Dublin Bay, resembles in outline a penta- 

 petalous flower, being slightly five-lobed. This peculiarity has not, I 

 believe, been noticed. Some time since, not knowing that it had been 

 described, I gave it the name of Tubulipora floriformis, to express 

 this peculiarity of form. To Mr. Thompson of Belfast the credit of 

 the discovery of this as a native zoophyte is due, a fact of which I 



