128 Rev, T. Hincks on 7iew species of British Zoophytes. 



wide, compressed, concave above, with an oblong aperture. Vesi- 

 cles small, quadrangular above, with a mucro at each comer on 

 the top, and a raised, circular orifice in the centre. 



Poli/pidom from 3 to 5 inches in height, simply pinnate, of a 

 rich blackish-brown colour, and very highly varnished; jnnn(e 

 alternate, slender towards the base, often much elongated, winged 

 or keeled along one side; cells opposite, adhei'ent for about half 

 their length, and then suddenly divergent, — the upper part wide, 

 compressed, rounded below, the superior surface concave, the 

 sides deeply indented, — aperture oblong, the outer margin 

 everted, the inner sinuated. Vesicles small, set along one side of 

 the pinnse, attenuated towards the base, subquadrangular above, 

 — a mucro (which bends inward) at each corner, and a raised 

 circular orifice in the centre. 



The vesicle bears considerable resemblance to that of <S^. pi- 

 naster, as figured by Dr. Johnston. 



Sertularia alata is nearly allied to the S. mvtulata, described 

 by Mr. Busk in the ' Voyage of the Rattlesnake,' and a native 

 of Torres Straits*. Besides other diff'erences, however, the vesi- 

 cles of the two species are perfectly dissimilar, — that of the 

 8. mutulatn beina: aculeate. 



Hab. Shetland"^ (Plate II.) 



New Polyzoon. 



A very minute zooph)i:e has occurred to me, creeping over the 

 surface of large mussel-shells brousht in from the Uo^-ger Bank 

 to the Yorkshire coast, which has hitherto escaped notice. I 

 have not yet had the opportunity of examining it in a living 

 state, but I have little doubt that it is a Polyzoon, and shall 

 assign it a place provisionally as such. 



Family Eucratiadce, Johnston. 

 „ Scrupariada, Busk. 



Genus Halia (Hincks). 



Pohjpidom adherent, creeping, corneous, branched ; cells de- 

 cumbent, adnate, irregularly disposed along the fibre, to which 

 they are attached at the base, or by a short stalk. 



Species: Halia prcttenuis (Hincks). 



Cells elongate, with upturned, terminal, and more or less 

 tubular apertures. 



The pohjpidom is a creeping fibre of great delicacy, irregularly 

 branched, corneous and closely adherent ; the cells, which occur 



* I am much indebted to Mr. Busk for his kindness in comparing the 

 Shethind Sertularia with the foreign species of the same genus. 



