Monthlj' Mlcrosoopicall 
Journal, Aug. 1, 1869. J 
On Holtenia. 
107 
IX. — On Holtenia, a Genus of Vitreous Sponges. By Wyyille 
Thomson, LL.D., F.E.S., Professor of Natural Sciences in 
Queen's College, Belfast. 
DuRiNa tlie deep-sea dredging cruise of H.M.S. ' Lightning ' in 
tlie autumn of the year 1868, the dredge brought up, on the 6th 
of September, from a depth of 530 fathoms, in lat. 59° 36' N. and 
long. T 20' W., about 20 miles beyond the 100-fathom hne of the 
Coast Survey of Scotland, fine, grey, oozy mud, with forty or fifty 
entire examples of several species of siliceous sponges. The mini- 
mum temperature indicated by several registering thermometers, 
was 47° • 3 Fahr., the surface temperature for the several locaHties 
being 52°-5 Fahr. 
The niud brought up consisted chiefly of minute amorphous 
particles of carbonate of lime, with a considerable proportion of 
living Glohigerinse and other Foraminifera, and of the " coccoliths " 
and " coccospheres," so characteristic of the chalk-mud of the warmer 
area of the Atlantic. The sponges belong to four genera ; one of 
them was the genus Hyalonema, previously represented by the 
singular glass-rope sponges of Japan and the coast of Portugal, 
and the other three genera were new to science. One of these 
latter is the subject of the present paper. 
Associated with the sponges were representatives, usually of a 
small size, of the Mollusca, the Crustacea and Annelides, the Echi- 
nodermata, and the Ccelenterata, with numerous large and remark- 
able tehizopods. Many of the higher invertebrates were brightly 
coloured, and had eyes. 
Four nearly perfect specimens of the sponge described in the 
memoir laid before the Eoyal Society were procured. 
Holtenia, n. g.* H. Carpenteei, n. sp. 
The body of this sponge is nearly globular or oval. Normal 
and apparently full-grown species are from 9" to 1' 1" in length, 
and from 7" to 9" wide. The outer wall consists of an open, 
somewhat irregular, but very elegant network, whose skeleton is 
made up of large separate siliceous spicules. These spicules are 
found on the hexradiate stellate type, but usually only five rays are 
developed, the sixth ray being separated by a tubercle. To form 
this framework of the external wall, the four secondary branches 
of the spicule spread on one plane, the surface of the sponge, while 
the fifth or azygous branch dips down into the sponge-substance. 
* The genus is named in compliment to Mr. Holten, Governor of the Faroe 
Islands, and the species is dedicated to Dr. W. B. Carpenter, V.P.R.S., with whom 
the author was associated in the conduct of the scientific expedition. 
