1900] MICROSCOPICAL JOURNAL. 335 



sist in regulating the current of water flowing through 

 the spoDge at large. 



As a kind of working classification based on the canal- 

 system of the calcareous group the following may be sug- 

 gested because the sponges included in it are easy to ob- 

 tain locally and are convenient to manipulate. But, as is 

 well known, the canal-system alone cannot be relied upon 

 to furnish a truly scientific classification, but it will serve 

 a present purpose in affording a kind of focus in. connec- 

 tion with which can be gathered the more important facts 

 which have guided spongologists in adopting a more elab- 

 orate arrangement. The attention of those who wish for 

 further information on the classification of this group is 

 directed to the Synopsis drawn up by Professor Dendy 

 and published in the "Proceedings of the Royal Society 

 of Victoria," vol. v. (new series). Subjoined is a simple 

 working classification alluded to above : — 



Calcareous Group. 

 Order I. — Homoccela, in which no flagellate chambers 

 are present, but the collared cells are confined to the 

 gastral cavity. Exs. Leucosolenia stolonifer, L. stipi- 

 tata and L. pulcherrima. 

 Order II. — Heterocoigla, in which the collared cells are 

 confined to the flagellate chambers. 

 Family I. — The flagellate chambers project freely. 



Ex. Sycon raphanus. 

 Family II 1 — The flagellate chambers are enclosed by 

 a cortex. (1). With radiate arrangements of cham- 

 bers. Ex. Sycon gelatinosum. (2)With chambers 

 scattered irregularly. Ex. Vosmaeropsis macera. 

 The names in the above list do not convey any idea of 

 the shape and size of the specimens selected as examples, 

 and it will be well, therefore, to state a few simple facts 

 in regard to their external appearance and habits of 

 growth as aids to discovery and identification, since one 

 specimen gathered and identified is of more practical value 



