March 9, 1900.] 



SCIENCE 



391 



fusing branches and chambers, are admirably 

 portrayed and their mode of origin from the 

 simple condition of an hypothetical rhagon-type 

 is clearly shown. The spicules have received 

 especial attention and the confusing nomencla- 

 ture is presented in a table where ninety-eight 

 different types of spicules are described and 

 named in accordance with the views of Sollas, 

 Leudenfeld, Stewart, and Schultze. With only 

 eight exceptions a figure of the spicule accom- 

 panies each description and with this table, an 

 average student for the first time, can classify 

 Sponges while the admirable schematic figures 

 of the organisms will help him to understand 

 their structure. 



The Sponges are divided as usual into two 

 branches, Calcaria and Incalcaeia. The for- 

 mer is subdivided into two orders, Homoccelida 

 and Heterocoelida (both adapted from Pol6jaef); 

 the latter is further divided into two sub-classes, 

 Triaxonice (F. E. Schultze) and Demospongise 

 (Sollas). The first sub-class includes two orders, 

 Hexactiuellida (Zittel, Leudenfeld) and Hexa- 

 ceratida (adapted from Leudenfeld) ; the sec- 

 ond sub-class includes three orders, Tetractin- 

 ellida (Marshall) Monaxonida (Ridley and 

 Dendy) and Mouoceratida (Leudenfeld). The 

 further divisions are made in accordance with 

 the nature and disposal of the spicules. An 

 improvement in the editing of the volume, al- 

 though of minor importance, is noted in the 

 presence of the name of the family to which 

 the various genera belong and this cannot fail 

 to help the student. 



As with the previous volumes disputed ques- 

 tions are clearly stated and the arguments on 

 both sides are fairly presented, the authors in 

 most cases taking a decided stand upon one 

 side or the other. If a critic wished to hunt 

 for defects in the work he might be successful 

 in the section which treats of the physiology of 

 nutrition ; this portion of the volume is not 

 complete enough. 



In connection with the taxonomic position of 

 the Sponges, the authors maintain with Hat- 

 Bchek, Perrier and Parker and Haswell that 

 they represent a phylum entirely distinct from 

 all other types. In their opinion one character 

 is sufficient to justify separation from the 

 Coelenterata and from all other groups. This 



feature is the fact first made out by Delage, 

 that the germ layer which corresponds to the 

 ectoderm of other Metazoa, passes during gas- 

 trulation to the interior, where it forms the 

 choanocytes in the walls of the ciliated cham- 

 bers, while the endoderm layer becomes super- 

 ficial and forms the definitive external cover- 

 ing. They also state that ontogeny throws no 

 light at all upon the relationships of the group. 

 Gary N. Calkins. 

 Department of Zoology, 

 Columbia Univeesity. 



A Memoir on the Palsezoic Reticulate Sponges con- 

 stituting the family Dictyospongidse. By James 

 Hall in collaboration with John M. Clarke. 

 (Memoir II, State Museum New York, 1898 

 [October, 1899], pp. 350, plates I-LXX, 

 royal 4to. A portion of this work also ap- 

 peared simultaneously with the same title, in 

 the Fifteenth Annual Report of the State 

 Geologist for the year 1895, Vol. II, pp. 743- 

 984, plates 1-47.) 



This volume is practically a continuation of 

 the 'Paleontology of New York,' and had its 

 inception in 1884. In 1890, but 42 species of 

 Dictyospongidse were known, and there are now 

 described and figured all the paleozoic repre- 

 sentatives of the living ' glass sponges,' of 

 which there are 128 species. "This wonderful 

 increase is not especially a matter for con- 

 gratulation, save that it serves to show the 

 amazing diversity of these silicious sponges in 

 late Devonian and early Carboniferous faunas." 

 All but 6 species are American. When the fact 

 is noted that most collections contain but few 

 specimens of these sponges, it is a surprise to 

 learn that 70 species alone are found in the 

 Upper Devonic of New York and Pennsylvania. 

 It is mainly in New York that the great fossil 

 ' sponge plantations ' occur, and these have 

 been and continue to be worked by Mr. Edwin 

 B. Hall of Wellsville, to whom belongs the 

 credit of having by far the largest collection of 

 these extinct forms. From some of the New 

 York localities several hundred specimens of a 

 kind have been taken, but usually a single spe- 

 cies is found in each or this may be even re- 

 stricted to one colony. 



Conrad (1842), was the first to record these 



