Exhibition of Sponges. 



235 



Bowerbank writes, " I am very busy just now on Dr Flem- 

 ing's ' Cydonium/ and there are a few points regarding the 

 original specimen that I shall be very glad to get information 

 about. I have just finished a monograph of 1 Spongilla.' 

 I have, besides our two British species, six from India, and 

 six from the river Amazon. I think this addition to the 

 fresh-water sponges will rather surprise our friend Dr 

 Fleming." In December 1855, Dr Bowerbank says, lt Dr 

 Flemings arrangement of the Sponge genera is — 



1. Tethea. 



2. Halichondria. 



Spongia. 

 Gkantia. 



" Dr Johnston in his ' Synopsis ' has — 



1. Tethea. 



2. Geodia. 



3. Pachymatisma. 



4. Halichondria. 



5. Spongilla. 



6. Spongia. 



7. Halisarca. 



8. Grantia. 



From both these forms of arrangement I feel strongly dis- 

 posed to dissent ; and with regard to the latter form, I think 

 Geodia and Pachymatisma, as being more highly organised, 

 should have precedence of ' Tethea and ' Grantia' should 

 take precedence of the whole. I therefore propose the fol- 

 lowing as the primary divisions of the tribe : — 



3. Keratose sponges. 



Calcareous sponges. 

 Silicious sponges. 



" The order of the existing genera would thenbeas follows: 



1. Grantia. 



2. Geodia. 



3. Pachymatisma. 



4. Spongilla. 



5. Tethea. 



6. Halichondria. 



7. Spongia. 



Halisarca merging into the Halicondracece. Spongilla, from 

 its highly organised reproductive system, and from the simi- 

 larity of those organs in many respects to those of Geodia 

 and Pachymatisma, requires that its position should be 

 between the latter genus and Tethea, Halichondria will cut 

 up into, at least, ten new genera. I am now very busy at a 

 paper for the Koyal Society, 1 On the Organisation of the 

 Spongiadce,' which must be published before my new ter- 

 minology can be understood. I intend to describe and 

 figure every normal form of every organ, with a definite name 



VOL. II. 2 H 



