Mr. Thompson on the Mollusca of Ireland. 101 



Sipunculus papillosum, mihi. 



&. vermiform, brownish white, skin striated concentrically and 

 covered with brown papillae. 



This is a fine and large species; throughout the greater 

 part of its length posteriorly, the papillae are more numerous 

 and larger on the two sides than on the dorsal and ventral 

 surfaces, and are particularly numerous at the posterior ex- 

 tremity, which is pointed and not perforated. It does not 

 appear to be parasitic. 



Specimens have been obtained at Miltown Malbay by 

 Mr. Harvey, and at the south islands of Arran (an adjacent 

 locality) by Mr. Ball. Mr. Harvey informs me that this 

 species is not uncommon under stones in sand-covered rocks 

 at Miltown Malbay. 



The last four species will be more fully treated of, and 

 figured, by Mr. Forbes, in his forthcoming work on the 

 British Echinodermata. 



Zoophyta. 



Flustra stellata, Membranipora stellata, mihi*. 



M. stellate, or of a sub-stellate outline, cells without hairs 

 or setae. 



Polypidom of a light sandy colour, encrusting the larger 

 marine Algae in somewhat of a stellate form ; a few 7 inches in 

 diameter ; aperture of the cells without hairs or bristles (like 

 those of M. pilosa'and M. spongiosa, Temp.f), but beset with 

 spines or denticles, varying much in number, one at the base 

 generally exceeding the others in magnitude. Along the cen- 

 tre of each ray extends a series consisting of a few rows of 

 oblong or roundish-oblong cells, on either side of w r hich are 

 transverse rows of square and roundish cells considerably 

 larger than those w T hich constitute the central portion ; " pa- 

 rietes of the cells prettily punctured J." This description 

 applies to the species in its most perfect state. When the 



* Considering all the generic characters of Flustra and Membranipora, 

 the present species would seem to appertain about as much to the " crus- 

 taceous" division of the former as to the latter genus. 



t Brit. Zooph. p. 282. This is identical with Flustra? carnosa, Johnston. 



X A character that I had overlooked, but which was noticed by Dr. 

 Johnston. 



