24 PORIFERA. I. 



ill the reo'ion of the osculmn hing so near the siirface, that the wall is here reduced to a thin, trans- 

 parent membrane; this is especiall>' the case, when the osculum is situated on the side of tlie sponge, 

 and then this part is often formed like a groove, and in this groove the osculum nia\' be more or less 

 retired. The pores are lying in the meshes of the dermal reticulation; they do not seem to be nume- 

 rous, and are very small, ca. o-02'""\ 



The skeleton consists of a rather dense, but irregular network of loose or not sharply marked 

 fibres or bundles of spicules, and in some places it seems to be only formed b}- irregular spread spi- 

 cules; most frequenth- the fibres or bundles contain man\- spicules. The dermal skeleton, as has been 

 mentioned, consists of an irregular and large-meshed net of spicules, and a similar one is found in the 

 membrane lining the inner hollow. 



Spiaila are slender oxea, .slightly curved in the middle; the>- decrease in thickness from the 

 middle towards the ends, and are long and finely tapering; thus they, as to their form, resemble the 

 needles of Halichondria paiiicea^ but they are longer than is common in this species, and most fre- 

 quently their curve is hardly so sharp. The length varies from o-b""" up to 0-92""", but in by far 

 the most cases it is 078"'"', the breadth is about o-oij"""; shorter and finer spicules are onl\- ver\' 

 rarely seen. 



Locality. Of this interesting species, which, though somewhat \-arying in form, is well charac- 

 terized by its single, spout-shaped osculum and the structure of this organ, the Ingolf-expedition has 

 taken ca. 15 specimens, station 27, 64° 54' Lat. N., 55° 10' Long. W., depth 393 fathoms; we have further 

 a couple of specimens, taken by the East-Greenland expedition 1891 — 92 at the south end of Jameson's 

 Land, dejutli 10 — 60 fathoms. Thus the species has hitherto been taken in the Davis Strait and at 

 the eastern coast of Greenland. 



H. oblonga Arm. Hans. 

 PI. II, Fig. 4. PI. IX, Fig. 10. 

 1885. Reniera oblonga Armauer Hansen, The Norwegian North-Atlantic Expedition XIII, 4, Tab. II, 

 fig. 5 A, Tab. VI, fig. 2. 



Erects more or less cylindrical. The surface grooved on account of the projecting ends of the 

 fbres. Osctila spread. The dermal membrane thin., zvithont spicules., pierced by the ends of the fibres. 

 The skeleton consists of fibres forming an irregular netzuork. A small amount of spongin present. 

 Spicula oxea, rather thick, and shortly and abruptly pointed, the length 0-41 — 0-44']""". 



Of this species we have four specimens, all rather cylindrical, of a length of 'i^-'i^ — 4-'" and a 

 diameter of 10—14"'™; they are, however, all broken off at the lower end; one specimen seems to ha\-e 

 divided into two branches above; according to this the tvpical form of the sponge seems to be cylin- 

 drical, erect, unbranched or with a few branches. The colour (in spirit) is light yellowish or brownish 

 gra>-. The surface is uneven and grooved, and the ends of the fibres project. The dermal membrane 

 that is supported by the ends of the fibres, is exceedingh- thin and transparent, and contains no spi- 

 cules; the examination of it is difficult, as it contracts when torn off. Oscula are rather numerous, 

 spread on the surface, of a diameter of ca. i"'"\ but somewhat \arying in size. On account of the diffi- 

 culty attending the examination of the dermal mem!:>rane, I ha\-e not with certainty seen an\- pores. 



