CHAP. IIL | THE CRUISES OF THE ‘PORCUPINE, 95 
and in the afternoon, rapidly passing over the edge 
of the plateau, we dredged in 725 fathoms with a 
bottom of muddy sand (Station 36). This is about 
the bathymetrical horizon at which we find the 
vitreous Sponges in the northern area; and although 
the bottom is here very different, much more sandy 
with but a slight admixture of globigerina ooze, we 
dredged a specimen, tolerably perfect though dead, 
of Aphrocallistes bocager, WRIGHT, a vitreous sponge 
lately described by Dr. E. Perceval Wright from a 
specimen procured by Professor Barboza de Bocage 
from the Cape-Verde Islands, and one or two small 
specimens of Holtenia carpenteri, Wy. T. The 
muddy sand contained a considerable proportion of 
gravel and dead shells. 
On Thursday, July 22, the weather was still re- 
markably fine. The sea was moderate, with a slight 
swell from the north-west. We sounded in lat. 47° 38’ 
N., long. 12° 08° W., in a depth of 2,485 fathoms 
(Station 37), when the average of the Miller-Casella 
thermometers gave a minimum temperature of 
Zo °C: 
As this was about the greatest depth which we had 
reason to expect in this neighbourhood, we prepared 
to take a cast of the dredge. This operation, rather 
a serious one in such deep water, will be described 
in detail in another chapter. It was perfectly suc- 
cessful. The dredge-bag which was safely hauled 
on deck at 1 o’clock on the morning of the 23rd, 
after an absence of 74 hours and a journey of up- 
wards of eight statute miles, contained 15 cwt. of 
very characteristic grey chalk-mud. The dredge 
appeared to have dipped rather deeply into the 
