Bibliographical Notices. 395 



admits that further observations are required to prove their distinct- 

 ness. The characters of the two named may be thus expressed : — 



Al. stagnorum, mass gray, polypes with 42-44 tentacula. 



Al. gelatinosa, mass yellowish or gray, polypes with 70 tentacula. 



Of the Plumatella we may confidently assert, that the history and 

 figures given by our author are very superior to any hitherto pub- 

 lished. His observations go to prove the distinctness of Plumatella 

 as a genus, but he has seen only one species, the variations of which 

 are not so prominent as to constitute them different in kind: "the 

 reciprocal resemblance of specimens to each other is not so striking 

 as at once to prove identity, though enough to establish kindred." 

 (p. 124.) The tentacula vary apparently from about fifty to seventy, 

 and Sir John says that the number certainly augments with age. 



Chapter 7 is devoted to " Ascidia." We must content ourselves 

 with a mere indication of the species described. 1. Ascidia villosa 

 = Pelonaia corrugata, Forb. 2. As. intestinalis, a species not de- 

 scribed by Forbes and Hanley. 3. As. rustica = As. scabra, Forb. 

 and Hani. The " young brood " of this represented on plate 35 is 

 surely a distinct species. 4. As. scabra = As. virginea, Forb. and 

 Hani. 5. As. mentula, a rare and gigantic species. " Specimens ob- 

 tained in the Orkney Islands are no less than 8 inches in height, 

 and 3 in their widest diameter." 6. As. papilla = Cynthia grossu- 

 laria. Van Beneden. This is fully described, and its mode of pro- 

 pagation ascertained. 



'• The Compound Ascidia" are described in Chapter 8, and five 

 plates are devoted to their illustration. We cannot undertake to 

 collate the species with those described by other authors, for the 

 subject is diflicult, and specific characters of ready apprehension 

 have not been given anywhere. Sir John denominates one kind 

 described by him Botryllus verrucosus ; but he has left the others 

 figured to be named by those who list. 



Chapter 9 contains good figures of some " asteroidal zoophytes," 

 viz. Lobularia digitata, Virgularia mirahilis and Pennatula phosphorea. 

 We need scarcely add that the history of each of them is given in 

 full and interesting detail. 



The "Actinia" or " the Animal Flower" is the subject of Chap- 

 ter 10, and the portraits of the species are exhibited in five plates. 

 After an excellent history of the genus, the author proceeds to de- 

 scribe the species whose habits he has studied with so much patience 

 and care. I. Actinia mesembry ant hemum. 2. Ac. cerasum=Ac. chio- 

 cocca, Johnst. 3. Ac. gemmacea = Ac. coriacea. 4. Ac.elegans,pro- 

 bably a new species. 5. Ac. explorator = Ac. troglodytes, Johnst. 

 6. Ac. lacerata = Ac. anguicoma, Price. 7. Ac. maculata =^ Adamsia 

 palliata. 8. Ac. dianthus. 



Chapter 11 is entitled "Miscellaneous Supplementary Observa- 

 tions." It contains some additional remarks on the Hydra tuba, 

 the story of whose singular metamorphosis formed such a charming 

 episode in the first volume ; and we have also another plate devoted 

 to its further illustration. It may be remembered that the Hydra 

 tuba, at uncertain epochs of its life, produced in succession, as from 



