136 
Bihliogy'aphicul Notices. 
withered by the deep corrosions of time ; sometimes it resembles 
a vigorous flowering shrub in miniature, rising with a dark brown 
stem and diverging into numerous boughs, branches and twigs, ter- 
minating in so many hydra?, wherein red and yellow intermixed 
afford a fine contrast to the whole. The glowing colours of the one 
and the venerable aspect of the other, their intricate parts, often 
laden with prolific fruit, and their numberless tenants, all highly 
picturesque, are equally calculated to attract our admiration to the 
creative power displayed throughout the universe, and to sanction 
the character of this product as one of uncommon interest and 
beauty.” (p. 51.) 
Very unexpectedly this remarkable zoophyte is proved by our au- 
thor to belong, not to the family Tubulariadae, but to the Sertularians, 
for it produces its germs in a prolific pod ” analogous to the vesi- 
cles of the SertularidB, and these germs are planules on their birth. 
“ Only a single large, bright yellow planule is contained in the ve- 
sicle, whence it is discharged on maturity from an orifice towards 
one side near the summit. But the vesicle itself is of such extreme 
transparence that it is hardly visible after losing its contents,” p.58. 
Perhaps we might remove the anomaly in its present place in the 
system by placing the species in the genus Thoa, of which it has 
the habit. 
4. Tubularia ramosa. The doubts which have been entertained 
of the distinctness of this as a species from T. ramea are now re- 
moved, for the two productions do not belong to the same family, 
the larva of the T. ramosa being medusiform. But its polype differs 
greatly from that of the genus Tuhularia as restricted in present 
systems, for while the head of the latter is naked and exposed and 
remains so under all conditions and circumstances, this can and does 
retreat within the tubular extremities of the polypidom for shelter 
(p. 65). 
5. Hydra viridis, pi. 12. figs. 17-20. 
6. Hydra fusca, pi. 12. fig. 15. The only species which the au- 
thor has found in Scotland. The figures are of the natural size, and 
very characteristic. 
7. Sertularia poly zonias. The most complete history of the spe- 
cies that has been published, and the figures are entitled to great 
praise. We here learn that the polypes or hydrae in the cells of 
the polypidom may die and be replaced after their decay by others, 
p. 149. The following passage on the food of these zoophytes is 
worth extracting : — “ The food of the smaller compound zoophytes 
is problematical ; but it is obvious that all must have subsistence to 
sustain life and promote enlargement. I was induced by the size of 
the hydra here to attempt feeding them with soft particles of the 
mussel, a substance the most grateful of any to most of the lower 
carnivorous tribes ; and I believe that I succeeded. I thought the 
particles might be discovered in the remoter parts of the stomach, 
whither they were transmitted by a distinct channel. There the 
contents a])peared as a dark internal mass, becoming ovoidal, and the 
hydra distorted. If the particle be too large, it is retained a long 
