On Holtenia, a Genus of Vitreous Sponges
Philosophical Transactions of the Royal Society of London
] XXVII. On Holtenia, a Genus o f Vitreous Sponges. W y v il l e T h o m so n , L L . BF .R.S. , Professor of Natural Science in Queen's , . D u r in g the deep-sea dredging cruise of Her Majesty's Ship «Lightning * in the autumn of the year 1868, the 6th of September was occupied in dredging at the depth of 630 fathoms in latitude 69° 36* N., and longitude 7° 2(V 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
... orth of the Butt of the Lews. The minimum temperature indicated by the mean of three ther mometers (which registered 47°, 47°*5, and 47°-6 F a h r . respectively) was 47°*3 F a h r , the surface-temperature being 52°'6 F a h r . 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 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 " Gulf-stream " area of the North Atlantic. The mud was glairy, as if it had been mixed with white of egg; ahd 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 A s t r o r h i z a, 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.