Plumularia. 
Z. HYDROIDA. 
147 
belong to PL pinnata. Aglaophenia setacea , L amour. Cor. Flex. 172. 
Corall. 76 Plumularia setacea, Lam. Anim. s. Vert, ii, 129. 2de 
edit. ii. 165. Flem. Brit. Anim. 547. Templeton in Mag. Nat. Hist. 
ix. 467. Stark, Elem. ii. 440. Bisso, L’ Europ. merid. v. 313 
La P. setacee, Blainv . Actinol. 477. 
Hah . Parasitical on other corallines, not uncommon. At Brigh- 
ton on flag, Lister. Frequent near Hartlepool, growing on the roots 
of the Palmated Fucus, Hogg . On scallop shells in the Frith of Forth, 
Jameson. Berwick Bay, G. J. Belfast Lough, Templeton. Cork 
Harbour, Thompson. 
In favourable sites this coralline will sometimes attain a height of 
six inches, but in general it is smaller, more delicate, and less plumous 
than PI. pinnata with which it has been confounded, although its 
habit and minuter characters prove it to be quite distinct. The stem 
is somewhat waved and regularly jointed, the joints consisting of two 
or three rings, and immediately under each joint the internode is 
somewhat enlarged in consequence of the pinna originating there, a 
single pinna only springing from under each joint, whereas in P. 
pinnata, as already remarked, three pinnae proceed from each inter- 
space, thejoints of which, moreover, consist of a single fracture. The 
pinnae are jointed like the stem, celliferous, the cells small and dis- 
tant. At the base of each there is a minute tubular process (abor- 
tive cell ?), visible only with a high magnifier. The vesicles are el- 
liptical, smooth, with a narrow plain orifice, and originate in the axils 
of the pinnae. — “ The ova within were opake and yellow. Its polypi 
had from sixteen to nineteen arms, and when they were full blown it 
was an object of remarkable beauty.” Lister. 
6. P- Cath arina, stem plumous , the pinnae opposite , bent 
inwards ; cells distant , campanulate with an even margin ; vesi- 
cles scattered , pear-shaped , smooth. G. J. 
Vignette, No. 8, page 79. 
Plumularia Catharina, Johnston in Mag. Nat. Hist. vi. 498, fig. 61, 62. 
Hah. On old shells, corallines, and ascidia in deep water. At 
Scarborough, rare, Mr Bean. Frith of Forth, Hr Coldstream . 
Frequent in Berwick Bay. 
This equals PL pinnata in size and delicacy, but differs from it very 
obviously in having opposite pinnae, which, instead of being arched, 
bend inwards, so as to render the general form of the coralline con- 
cave on a front view ; an appearance produced by the pinnae origi- 
nating, not from the sides, but from the anterior face of the stem. 
The stem itself is straight or slightly bent, jointed, pellucid, filled 
with a granular fluid matter ; and, in which it differs from its 
congeners, bearing cells, there being always one at the base and be- 
tween the insertion of the pinnae, and generally another on the 
