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gnaw, but is obliged to wait till a piece comes adapted to his swallow ; and 

 that is much more likely to be an active moving animalcule than an alga 

 spore, the only vegetable substance to be had in any quantity in the sea. 

 I think we may safely conclude, therefore, that the food of all Polyps con- 

 sists chiefly of living animals of no considerable size, and that, in particular, 

 the small and partly even microscopical Tunicata, the fry of Mollusca, the 

 minute marine Annelids and Crustacea which illuminate the surface of the 

 ocean by night with innumerable sparkles of phosphorescent splendour, con- 

 stitute the principal substances which the Polyps assimilate for their suste- 

 nance and growth." 



The arrangement of the Animal world, which Burmeister follows in the 

 present work, is, in a great measure, an amplification, and a more scientific 

 filling up of the sketch which forms the concluding portion of his " History 

 of the Creation," in the shape it wears in the latest edition. In the main, 

 he has not departed from the principles of the classification proposed, a 

 quarter of a century since, in his " Class-book of Natural History," and 

 which was exhibited more at large in the " Manual of Natural History," 

 1837. The investigations of late years, so diligently pursued, and with 

 such fruitful results, regarding the structure and history of the lowest 

 classes of animals, it is true, have afforded much new materials, of which 

 he has not been slow to avail himself here ; but this has tended rather 

 to complete what remained imperfect, and to elucidate that which was 

 obscure heretofore, than to effect a revolution in the ground plan of 

 the system generally. Accordingly, we find the Bryozoa still ranked among 

 his Polyps, yet not without a distinct acknowledgment of the tendency 

 among them to bilateral symmetry, which, with certain other characters, 

 has induced some of the most accomplished zoologists of the present day 

 to place them rather in the Molluscan series, and next to the Tunicata. 

 The Rotifera are still arranged under Crustacea, and the Myriapoda 

 continue associated with the Arachnida. The Polypi and the Acalepha, 

 among the Regular animals, are treated with much particularity and some 

 apparent predilection ; all these, as well as the Irregular animals, in the 

 first of these two volumes. The Symmetrical animals commence with the 

 second volume. For the specialities in the class Mollusca, Burmeister has 

 availed himself of the able assistance of his former pupil, Dr. Giebel. The 

 classification of the Worms is, perhaps, the portion of the work which is 

 stamped most strongly with originality. Commencing, as is usual, with 

 the intestinal worms (Helminthes), the most simple of the class in their 

 organization, Burmeister adopts the conclusions of Lieberkuhn, assigning 



