136 Bibliographical 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 hydrse, 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 Tubulariadse, but to the Sertularians, 

 for it produces its germs in a ** prolific pod " analogous to the vesi- 

 cles of the Sertularice, 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. Tuhularia 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 fu^ca, 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 polyzonias. 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 hydrse 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 ajjpeared as a dark internal mass, becoming ovoidal, and the 

 hydra distorted. If the particle be too large, it is retained a long 



