118 
Z. HYDROIDA. 
Tubularia. 
This coralline so perfectly resembles a tree in miniature, deprived 
of its leaves, that persons unacquainted with the nature of zoophytes 
cannot be persuaded that it is not of a vegetable nature. It is from 
3 to 6 inches high, rooted by a densely interwoven mass of tubular 
fibres, which by their cohesion and intertwining form the stem, which 
is sometimes as thick as the little finger. This is irregularly divided 
into many compound branches, formed like the stalk itself, but the 
ultimate branches consist of a single short tube, ringed at the base, 
and terminated by the non-retractile polypes. The separate tubes 
are filiform, not thicker than ordinary thread, of earthy brown colour, 
horny, wrinkled at intervals. The polypes placed at the extremities 
of the branches are of a reddish colour and appear indolent in dispo- 
sition, contracting slowly under external irritations : they have about 
twenty whitish tentacula arranged in one row round a broad oral 
disk. 
It is possible this may be a state of T. ramosa, but its arborescent 
character and the complexness of its structure are so remarkable 
that I have willingly followed the example of Pallas, who has given 
a description of the species in his usual accurate and expressive style. 
I find it noticed by no other author, unless perhaps by Otho Fabri- 
cius, but his description is not sufficiently explicit to remove all 
doubts of the correctness of his synonyme. The Sertolara racemosa 
of Cavolini, Polip. Mar. p. 160, tav. 6, fig. 1, is a nearly allied 
species. 
The Tubularia flabelliformis of Adams in Lin. Trans, v. 
12. ( Turt . Gmel. iv. 669. Turt. Brit. Faun. 211. Stew. Elem ii. 438.) 
is a minute parasitical alga of the family Diatomaceae. 
