Dec. 19, 1889J 



NATURE 



H7 



slls us, his time was chiefly spent in the zoological labor- 

 Itory of Prof. F. E. Schulze, then engaged on those re- 

 earches on the natural history of sponges with which 

 is name will ever be associated. This led him to take a 

 ;)ecial intest in the group, and to work out its history, 

 irst in the Mediterranean, and then at Melbourne and 

 other places on the southern coast of Australia — a coast 

 exceedingly rich in organisms of this class. From Mel- 

 bourne, New Zealand was visited, and the Christchurch 

 and Dunedin collections were examined. Next, that ap- 

 parent El Dorado of the spongologist, Sydney, was ex- 

 plored, and, thanks to the splendid liberality of Sir 

 William Macleay, Lendenfeld was enabled to establish 

 a laboratory at the water-edge, and to study in a very 

 thorough manner the sponges of this district. 



With such abundant material, and with such ready 

 help, nothing was wanting to work out the structural his- 

 tory of the species of the group. But to describe and 

 name them, reference to type specimens was, above all 

 things, necessary, and these latter were to be found most 

 conveniently in the British Museum ; thither, therefore, 

 Lendenfeld came, early in 1886, at first resolved to write 

 an account of the Australian Horny Sponges ; but for- 

 tunately finding, during the progress of this work, that 

 so great a proportion of the known forms were Austra- 

 lian, he determined to make a complete monograph of 

 the group, and hence the volume which we proceed to 

 notice. 



This monograph of the Horny Sponges is divided into 

 three parts : (i) an introduction, containing a brief his- 

 torical summary and a detailed list of publications relat- 

 ing to sponges ; (2) an analytical portion, devoted to the 

 systematic description of all the known Horny Sponges ; 

 and (3) a synthetical part, in which the anatomy and 

 physiology of sponges, especially of Horny Sponges, are 

 treated, and their phylogeny, systematic position, and 

 classification discussed. 



Of the very extensive and scattered literature relating 

 to the sponges, a most excellent bibliography is given ; 

 the papers are arranged alphabetically under their authors' 

 names, but the publications of each author are given 

 chronologically ; the number of pages in each memoir is 

 given, but, unfortunately, no reference is made to illustra- 

 tions ; abstracts and translations of papers are always 

 quoted. 



Considering the genus as " the important unit," the 

 analytical part consists essentially of a series of mono- 

 graphs of the genera of Horny Sponges, but " species " 

 as such are described ; and the author has " done his 

 best to make the different species equivalent," though 

 this has been difficult of achievement. In those cases 

 where he has felt compelled to establish varieties, he has 

 followed the plan of E. Haeckel and F. E. Schulze, and 

 has divided the whole species into "the requisite number 

 of equivalent varieties." The total number of the species 

 and varieties described amounts to 348, of which no less 

 than 258 have been found in the Australian area. 



It would not be possible, within any reasonable space, 

 to give any satisfactory details of the analytical portion 

 of this monograph. The descriptions of each genus are 

 grouped into — an historical introduction ; a sketch of the 

 shape, size, colour, surface, and rigidity characteristic of 

 tlie group ; an account of the canal system, skeleton, 



with notes on the histology and physiology ; the affinities 

 of the genus ; statistics of the species, with a key thereto, 

 and details of distribution. Doubts must of necessity 

 arise as to the exact limits that each author would ascribe 

 to the species described by him, and in doubtful cases of 

 this sort Dr. Lendenfeld has adopted the plan of placing 

 no authors' names after them, but gives a full list of 

 synonyms ; we think it a pity that in these lists the memoirs, 

 instead of being quoted, are simply referred to by num- 

 bers, for the explanation of which one must refer to the 

 bibliographical list. 



It is in the synthetical part, in which the general re- 

 sults are discussed, that the chief interest of this work 

 lies, at least for the general reader. Here we have the 

 questions of the general structure and evolution of sponges 

 as a group considered, and their classification and sys- 

 tematic position discussed ; and finally, as the fashion 

 of some authors is, " an ancestral tree of the families " 

 is given. Starting with the story of the metamorphic 

 development of sponges, we find the primitive sponge 

 defined as consisting of a simple ento- and ectoderm, 

 and a thin mesogloea — a very primitive mesoderm — be- 

 tween the two. Dr. Lendenfeld thinks that it is now 

 generally acknowledged that the Physemaria, which 

 Haeckel considered as " Gastreaden der Gegenwart," are 

 not sponges at all, but Protozoa, so that they need not 

 here be taken into account. Of course, it is evident that 

 the views about these Physemarias, held at present by 

 Haeckel, were, at the time of his thus writing, un- 

 known to Dr. Lendenfeld. The modified Gastraea is 

 traced onwards in its development, and the morphology 

 of the adult structures are passed under review ; their 

 want of symmetry — and the exceptions are but few — is 

 noted. None of the Horny Sponges are green ; blue is 

 never observed in the group, the range of colour being 

 from light yellow to dark brown, light to dark red, and 

 light to a dark, almost black, violet ; the colour is lost in all, 

 with a few exceptions, such as inAplysillaviolacea, when 

 the sponge is preserved. The Horny Sponges would 

 seem never to imitate their surroundings in colour, but 

 it is suggested that in some cases the intense vivid 

 colours may have the effect of frightening their enemies. 



An attempt is made to account for the shape of the 

 sponge conuli as the result of two pressure forces and to 

 express this by formula. The biological student will 

 scarcely be grateful for this, and is likely to be bewildered 

 when he reads that " the conuli are hyperbolic rotatory 

 bodies, formed by the rotating of the hyperbola, 



y={p. x)i(/ + t . X), 



round an axis parallel to the direction of pressure through 

 the summit of the conulus." The canal system is de- 

 scribed in some detail, the author not confining himself 

 to the Horny Sponges. In contrasting this system in the 

 Hexactinellida and the Hexaceratina, there seems some 

 little confusion as to the comparative " tenderness " of the 

 structures. The absence of spicules (siliceous) in the 

 fibres is considered as the characteristic feature of the 

 Horny Sponges, which distinguishes them from their 

 siliceous ancestors ; but in the superficial fibres of Aulena, 

 echinating proper spicules occur ; in the ground sub- 

 stance of several genera of Spongeliadae, microsclera are 



