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XXVII. On Holtenia, a Genus of Vitreous Sponges. By Wyville Thomson, LL.I)., 
F.B.S., Professor of Natural Science in Queen's College , Belfast. 
Received June 16, — Read June 17, 1869. 
During the deep-sea dredging cruise of Her Majesty’s Ship 4 Lightning ’ in the autumn 
of the year 1868, the 6th of September was' occupied in dredging at the depth of 580 
fathoms in latitude 59° 36' N., and longitude 7° 20' W., only about 20 miles beyond the 
100-fathom line of the Coast Survey of Scotland, slightly to the westward of north of 
the Butt of the Lews. The minimum temperature indicated by the mean of three ther- 
mometers (which registered 47°, 47 0, 5, and 47°’5 Fahr. respectively) was 47 0, 3 Fahr, 
the surface-temperature being 52°-5 Fahr. 
During the day there were four successful hauls of the dredge, which came up each 
time full of a pale-grey tenacious mud, consisting in a great measure of minute amor- 
phous particles of carbonate of lime mixed with “coccoliths” and 44 coccospheres.” 
There was only a small proportion of the Globigerince and other minute Rhizopods which 
are so abundant and characteristic over the whole of the warm or 44 Gulf-stream ” area 
of the North Atlantic. The mud was glairy, as if it had been mixed with white of egg ; 
and it contained disseminated through it an immense quantity of extremely delicate 
siliceous organisms, spicules of sponges, and the shells of Radiolarians and Diatoms. 
Large Rhizopods of the genera Astrorhiza, Bhabdammina, Cristellaria , Cornuspira, and 
others were abundant ; and there was a somewhat scanty sprinkling of small forms belong- 
ing to the higher groups, Echinoderms, Annulosa, and Mollusca. Besides a number of 
dead shells, chiefly of the Boreal or Scandinavian type, and several undescribed Echino- 
derms and Crustaceans, the following species were procured living. 
Echinodermata. 
f Bhizocrinus Loffotensis , Sars, 
Amphiura fliformis, Muller. 
f Ophiacantha spinulosa, Muller 
and Troschel. 
* \Echinocucumis typica, Sars. 
f Thyone alticola, Norman, MSS. 
Amphiura tenuispina, Ljungman. 
Amphiura Ballii , Thompson, 
f Amphiura Abyssicola , Sars, 
Crustacea. 
Phoxus plumosus, Kroyer. 
Ampelisca cequicornis, Lilljeborg. 
f (Ediceros spinicornis , Norman, MSS. 
Haploops tubicola, Lilljeborg. 
f Diastylis (sp.). 
Pagurus pubescens, Kroyer. 
Galathea dispersa, Bate. 
MDCCCLXIX. 
5 A 
