25 
In fig. 122, plate IV. I have given an illustration of the par- 
ticular oscular tube, as it is described by Sollas; but as he had 
only seen a very young specimen so I thought it not bad to illus- 
trate a very large one. Sollas says that the canals communicate 
directly with the chones in which are the sphincters. But it this 
big specimen from Hammerfest I saw that between the excurrent 
chones and the large excurrent canals there is yet a system of 
erypts, as I have figured on plate IV, fig. 121. It seems to me that 
these main canals which are arranged around the oscular tube have 
sideward communications with the crypts, and that these are sepa- 
rated from the oscular tube by means of the wellknown sphincters. 
These great canals are conspicuous for being rather, white, while 
the surrounded mass in which they are imbedded is more yello- 
wish. The walls of these canals show the same rugae as in the 
described Synops. 
10. Tethya Iyncurium var. obtusum [Pl. IV, fisg. 123—126]. 
Diagn. Corpus globosum , per radicibus inhaerens. Spieula indicantia : 
(eneaest. | tr. fe-8. ost. | 
Local. Lat. 71° 12'5N.; long. 20° 30'E. (1879). 
Geogr. distrib. of the species: Mediterrenean; Adriatie Sea; Atlan- 
tie Ocean. 
Depth. 135 Fathoms. 
There were dredged up two small specimens of this Tethya, which 
is perhaps a distinet species; but as I have had occasion to see. 
a great quantity of Tethya Iyncurium from the Adriatic and Medi- 
terrean seas, and often had opportunity to observe that these are 
varying in the most extraordinary way, so I must include also 
the specimen under description to T. Iyncurium. I will publish my 
observations on Tethya lyncurium afterwards; but I will for the 
moment only mention the fact that this Sponge varies 1°. in colour 
(ochreous yellow, clear yellow, orange, red). 2°. In the appea- 
rance of the papillae; one time they are closed together, and end 
‚broadly, so that the Sponge appears compact another time (often 
in the same subject) they are standing far one from another, a 
