97 
gams, their markings produced by gelatinizing silica, and resem- 
bling the dendritic appearance of many opaline minerals ; but 
Dr. Frazer believed, from his observations, that the true cause of 
the latter markings was arborescent forms of red and brown oxide 
of manganese. 
Professor E. Perceval "Wright exhibited a specimen of Hyalo- 
nema, which he had dredged up from a depth of 480 fathoms, 
about thirty miles to sea, off the coast of Setubal, near Lisbon. 
He exhibited the beautiful arrangement of one set of spicula, 
which form a delicate, open network, covering the otherwise open 
oscula. He stated that he regarded the siliceous axis as the stem 
of the sponge mass, called Carteria by his friend, Dr. J. E. Gray, 
and that he had determined that the end of the axis — as had been 
suggested by Loven — where the fibres become loose, is that one 
imbedded in the mud, the sponge mass crowning the summit, and 
presenting a somewhat different form in different specimens, 
though Dr. Wright would here remark that he inclined to believe 
that almost all the species referable to Wyville Thomson’s Order, 
Yitrea, will be found to be pretty constant in their external forms. 
From the examination of perfect specimens — now r for the first 
time — will it be possible to determine the exact position in this 
sponge of all the beautiful spicula figured by Dr. Bowerbank, 
Max Sehultze, and others. 
When the sponge mass is washed away or destroyed, then the 
parasitic Palythoa, which appears to be very common, grows up 
over that portion of the stem left uncovered by the mud, and 
presents the appearance figured by Brandt and others. Speci- 
mens of this parasite were seen protruding their tentacles, a suf- 
ficient answer to the supposition of Bowerbank that they are the 
oscula of the sponges. Mouths they have certainly, but not at the 
service of the sponge (Hyalonema). 
The Hyalonema would appear to occur at this depth in great 
quantities ; and in addition to the Palythoa, an Adamsia, a Sertu- 
larian, and some pretty specimens of a Pollicipes, were all found 
living, attached to its glassy stem. Professor Wright was greatly 
indebted to Professor Bocage, of Lisbon, for his assistance in these 
researches. 
Mr. Archer cursorily exhibited a few new or rare forms of 
Desmidieae, chiefly Staurastra, taken on an excursion to County 
Galway, in company with Dr. Barker ; as, however, he had not 
yet had time to examine them with all the critical care requisite, 
he could only hope to return to them more minutely on another 
occasion. A few forms in Cosmarium and Staurastrum he thought 
he must defer till perhaps some time or other he might have an 
opportunity to compare them with certain Continental forms ; two 
or three he might describe as new on his own authority, whilst 
two or three more were identical with others occurring nearer 
home, which he had for some time in his mind’s eye as new, but it 
would be a work of patience and delay to see authentic examples 
of foreign forms. A few British forms turned upon these gather- 
VOL. IX. NEW SER. G 
