ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 63 



of sponges, and of their distribution, as to which our information is very 

 fragmentary. After a selected list of works treating on sponges, Prof. 

 Sollas gives an account of the mode of taking, cultivation, and prepara- 

 tion for market of officinal sponges. 



Skeleton of Calcareous Sponges.* — Prof. V. v. Ebner has submitted 

 the spicular skeleton of calcareous sponges to a searching analysis, and 

 comes to the conclusion that the spicules are always " bio-crystals." 

 " The spicules are mixed crystals, mainly composed of calc-spar, 

 containing no organic material ; the outer form is without the true 

 crystalline contour, but is determined by the specific activity of the 

 organism ; the internal structure, though perfectly crystalline, stands in 

 relation to the external form by a peculiar distribution of the mixed 

 ingredients." The mixture of salts is due to contemporaneous excretion 

 of more than one. More briefly he reviews the skeleton of calcareous 

 Algae, Foraminifera, Ccelenterates, and Eehinoderms, in which marked 

 ^differences, and at the same time, striking resemblances occur. " In the 

 formation of bio-crystals the crystallograpbic orientation of the substance 

 first excreted is alone determinative, and all the rest of the substance is 

 formed on the above foundation according to the laws of crystallization, 

 without special activity of the protoplasm, which has only a moulding 

 influence on the external form and on the mixture of material. When, 

 however, organic material is excreted along with the calc-spar, as in the 

 calcareous membranes of corallines and spicules of corals, there is no 

 longer a uniform crystallization." It is still a crystalline excretion, but 

 the molecules of carbonate of lime arrange themselves in a fashion " in 

 general like that found in non-calcified, doubly-refractive tissues." 



New System of Chalininae.f — Mr. A. Dendy has some criticisms on 

 a recent publication by Dr. E. von Lendenfeld dealing with the Ch&Iininaa 

 of the Australian region. He points out that the generalization that 

 there are no incrusting Chalinids is contradicted by Dr. Lendenfeld's 

 definition of his new species Hoplochalina incrustans. There are some 

 important divergences between the letterpress describing, and the 

 figures illustrating the canal-system, the latter giving representations of 

 certain remarkable funnel-shaped canaliculi, such as neither Mr. Dendy 

 nor any other author has yet found in a Chalinid sponge. 



The systematic classification of the Chalininae is severely dealt with, 

 and evidence is afforded of Dr. von Lendenfeld having adopted in the 

 main the classification of Messrs. Eidley and Dendy, " but instead of 

 giving it in the way we gave it, and with the significance which we 

 attached to the different groups, he has modified it to suit his present pur- 

 poses, thereby, in my opinion, almost entirely destroying its value." 

 Spicules, it is .urged, not spongin, must be taken as guides to classification. 



Fresh-water Sponges.} — Mr. E. Potts has published a synopsis of 

 the known American forms of fresh-water sponges, with descriptions of 

 those named by other authors, &c, from all parts of the world. After a 

 general account of their structure, and of the means of collecting, 

 observing, and mounting them, the author justifies his method of nomen- 

 clature. 



From imperfect memoranda Mr. Potts finds that he has examined 



* SB. Akad. Wiss. Wien, xev. (1887) pp. 55-148 (4 pis.). 



t Ann. and Mag. Nat. Hist., xx. (1887) pp. 326-37. 



j Proo. Acad. Nat. Sci. Philad., 1887. pp. 158-279 (8 pis.). 



