CRISIAD^ : CRISTA. 285 



Hah. " On corallines, not rare, from various parts of the coast," 

 Fleming. 



Polypidom erect, about an inch in height, white and calcareous, 

 bushy, dichotomously divided, the branches inclining inwards ; the 

 joints jet-black ; the internodes narrow at their origin, widened 

 upwards ; the cells entirely adnate, tubulous, semi-alternate, thickly 

 specked with granules disposed in rows, the apertures shortly tubu- 

 lar, secund, with a circular even slightly thickened rim. 



Though in many respects similar to the preceding, this is yet 

 essentially different, and has been well characterised by Dr. Fleming. 

 It is of a denser texture ; the branches, or rather the spaces between 

 the joints, are longer, broader and thicker in the middle ; the cells 

 are more closely connected ; their orifices are not detached from the 

 sides, and the joints are black, so that the polypidom appears dotted 

 to the naked eye. 



S. 0. ACULEATA, " cbUs clisposed ill a double series, armed with 

 a long spinous process, joints of an amher colour.'''' A. H. 

 Hassall. 



Crisia aculeata, Hassall in Ann. and Mag. Nat. Hist. vi. 170, pi. 7, fig. 3, 4 ; and 

 vii. 366. — Crisie ivoire, M. Edivards in Ann. des Sc. Nat. n. s. ix. 198, pi. 6, fig, 

 2. — Crisia eburnea, Van Beneden Recherch. 52, pi. 6, fig. 12-16. (Without the 

 spinous processes.) 



Hah. Brighton ; not unfrequent, A . H. Hassall ; who subsequently 

 added it to the Irish Fauna, having found it on stones east of 

 Kingstown harbour. On a valve of Pecten maximus dredged be- 

 tween Larne and Glenarm, co. Antrim, R. Patterson. Found at Bal- 

 lantrae, Ayrshire, in 1839 ; and in Strangford Lough, in October of 

 of the same year, W. Thomijson. 



" Polypidom erect, bushy, about an inch in height, and beauti- 

 fully frosted ; branches alternate, jointed at irregular intervals ; in- 

 ternodes narrow at their commencement ; cells subalternate, tubular, 

 the majority being furnished with a long spine, which arises from 

 the outer side. Vesicles much resembling a fig in shape, and 

 dotted." A. H. Hassall. 



" Milne-Edwards has figured this species, which I described in 

 the ' Annals of Natural History* for November 1840, in the ' Annales 

 des Sciences Naturelles' for April 1838, under the name of La 

 Crisie ivoire. How Milne-Edwards could have confounded this 

 somewhat rare species with the common one, C ehurnea, I am at a 



