90 
has brought out a large memoir on the Sponges of the Atlan- 
tic bottom, in which some new forms of siliceous sponges are 
described, and the characters of others given. Mr. W. Savile 
Kent, of the British Museum, dredging in the Norna with 
Mr. Marshall Hall, and using his eyes in the museum of 
Lisbon and elsewhere, has this year added greatly to our 
knowledge of these forms. It will be remembered that much 
interest was excited by the discovery by Dr. Thomson of 
Holtenia, an ally of Hyalonema. Mr. Kent has added a 
new species to each of these genera, showing also that Hol- 
tenia is probably the Pheronema of Leidy. He has also 
discovered two new genera, Askonema and Dorvillia, belong- 
ing to the same group, of which he has read an account to 
the Microscopical Society. ‘Two other genera, not so closely 
allied to Hyalonema, have also been discovered by Mr. Kent. 
We subjoin his list of this interesting and beautiful group of 
sponges, characterised by their hexradiate spicula. 
Order HEXACTINELLIDA. Oscar Schmidt. 
Sponges with a siliceo-fibrous or siliceo-spicular skeleton. 
oye ey! 
Spicula of the hexradiate-stellate type invariably present. 
Sub-Ord. I. Coraruiosponcia. J. E. Gray. 
Sponge body supported by an anastomosing or continuous 
reticulate skeleton. Reproductive gemmules entirely mem- 
branous, aspiculous (?). 
Gen. Euplectella, Owen. 
Habrodictyon, Wyv. 
Thomson. 
Aphrocallistes, J.E.Gray 
Farrea, Bowerbank. 
Gen. Aulodictyon, W.S. Kent. 
Macandrewia,J.E.Gray. 
Dactylocalyz, Stutch- 
bury. 
Freldingia, W. 8. Kent. 
Sub-Ord. II. Catuictsponcim. W.S. Kent. 
Sponge body supported by an interlacing or isolated spi- 
cular skeleton; never by a reticulate and continuous one. 
Reproductive gemmules membranous, furnished with protec- 
tive spicula (?). 
Gen. Pheronema, Leidy. Gen. Lanuginella, Oscar 
Hyalonema (et Carteria), Schmidt. 
Gray. Vazella, Gray. (Holte- 
Pe W.S. Kent. nia pars, Oscar 
Sympagella, Oscar Schmidt). 
Schmidt. Dorvillia, W. 8. Kent. 
Microbotany. Diatomacee.—Count Castracane has lately 
been engaged sifting and classifying the new forms of diatoms 
he discovered in the muddy deposits of the Atlantic dredging, 
