#1^ Bibliographical Notices. 



The fibre in the dry state is exceedingly rigid and brittle^ and 

 preserves much of its rigidity even after having been soaked 

 many hours in water. The radiation of the fibres from the centre 

 of the sponge towards the outer surface is in a series of straight 

 lines^ and the interstices rarely exceed half a line in length. 



The great excurrent canals are found only on the extreme edge 

 of the sponge j they are few in number^ and are disposed in a 

 single line at unequal distances throughout the whole of the 

 circumference of the sponge, the largest not exceeding two lines 

 in diameter. 



This sponge is remarkable for its approximation, in the struc- 

 ture of its skeleton, to the highest orders of animal organization. 



BIBLIOGRAPHICAL NOTICES. 



A History of the British Freshwater AlgcB, including descriptions of 

 the Desraidese and Diatomacese, with upwards q/" 100 Plates. By 

 A. H. Hassall, F.L.S. 2 vols. 8vo. London, 1845. 



We consider the publication of this work as likely to promote in a 

 great degree the study of the freshwater Algae of Britain ; a tribe 

 which, owing to its great obscurity and the want of good magnified 

 figures, has been almost universally neglected by our botanists. 

 Whilst the Mosses, the Lichens, the Fungi, and even the marine Algae 

 have had valuable and elaborate works devoted to their elucidation, 

 we are not acquainted with any extensive English work on the fresh- 

 water tribes since that of Dillwyn, which, although highly valuable, 

 having appeared before the structure of the Algae was much under- 

 stood, cannot be considered as supplying the deficiency. The figures 

 contained in Mr. Hassall's work will be found of the utmost value to 

 the student of this curious tribe of plants, as they appear in most 

 cases to have been carefully drawn and to be faithful representations 

 of the species. It is unfortunate that the author has not pointed out 

 the cases in which his figures are not the result of his own observa- 

 tions, but copied from published plates. The appearance of " Hass, 

 delt." at the bottom of all the plates leads us to suppose that they 

 are all of them original, but a more careful examination shows that 

 not a few are copies. We shall notice some of these as we proceed, 

 previously however reminding cur readers that the parts of the book 

 which it falls to our lot to blame are only a small portion of the 

 whole. As a whole, there can be no doubt that it is a proof of its 

 •author being possessed of very considerable abilities ; more especially 

 of extensive powers of discrimination, although not of definition. 

 We consider these powers as quite distinct and frequently existing 

 separately, although both are essential to a writer on descriptive 

 natural history. 



In the preface we find it stated that " the characters developed 

 in the state of reproduction are relied upon in the framing not merely 

 of the families and genera, but also in the definition of species " in the 



