GENERAL ZOOLOGY. 77 



a place, the lowest, among them, to certain Unicellular animals (Mono- 

 cystis, &c.) ; the Gregarince following next, — while he disposes of the 

 Psorospermia in a somewhat different way, as merely embryo forms of 

 these. With the Trematodes and Planarise the Leeches also are asso- 

 ciated in one order (Platodes), Flat worms. The Round worms (Gymno- 

 dermi) include the families Siphunculini, Priapulidae, and Echiuridse, — all 

 comprehended under the common appellation of Mud worms (Gephyrei), 

 — as well as the proper Nematodes. In the remaining order, Annelides, 

 Burmeister's divisions do not vary materially from the views of Grube, 

 except as regards the removal of the Leeches from this order by the 

 former. 



The two volumes published bring us as far as to the end of the 

 Arachnida. There remain, then, of Arthropoda the entire vast class 

 Insecta, and the sub-kingdom Vertebrata, for the subject matter of another 

 volume. Burmeister has briefly indicated here the mode of treatment he 

 contemplates in regard to these ; the space reserved for the Insects being 

 very strictly limited, in consideration of the length at which he has 

 handled them already in other works devoted to that class specifically. 

 The promised appearance of the concluding volume is postponed, however, 

 until the author's return from the second travels, which he has newly under- 

 taken, in South America. We will not here anticipate the criticisms we 

 may be again obliged to enter into, when Burmeister shall have reached 

 the culminant point in the scale of animal organization, at the deferred 

 conclusion of the " Zoonomic Letters f for he has betrayed, of late, a 

 wavering in his allegiance to the views he had embraced before, in common 

 with all the most eminent names in Zoological science, touching another 

 doctrine of not less interest than that agitated in the earlier letters, and on 

 which we have already remarked. Bather let us wish him, on his distant 

 pilgrimage, health and the bland favour of propitious elements ; along 

 with which, large gatherings of scientific fruit, for the materials of future 

 instruction and entertainment of many readers, and ourselves included. 



A. H. H. 



Manual of the Botany of the Northern United States. By Asa 

 Gray, Fisher Professor of Natural History in Harvard University. Second 

 Edition. New York. 1856. 



This work, designed for the use of students and practical botanists in the 

 United States, will be found very useful to all persons in this country who 

 may have received collections of dried plants from transatlantic friends or 



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