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 ' 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, Dr 
Fleming's arrangement of the Sponge genera is — 
1. Tethea. 3, Spongia. 
2. Halichondria. 4. Grantia. 
" Dr Johnston in his ' Synopsis ' has — 
1. Tethea. - 5. Spongilla. 
2. Geodia. 6. Spongia. 
3. Pachymatisma. 7. Halisarca. 
4. Halichondria. 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 : — 
1. Calcareous sponges. I 3. Keratose sponges. 
2. Silicious sponges. | 
" The order of the existing genera would thenbeas follows : 
4:. Spongilla. 
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, ' On the Organisation of the 
Spongiadoi,' 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 
1. Grantia. 
2. Geodia. 
3. Pachymatisma. 
5. Tethea. 
6. Halichondria. 
7. Spongia. 
