.-, PORIFERA. I. 



40 



ridges, and is somewhat grooved; it is finely shaggy from the projecting spicules. The drrmal monbrmie 

 is thin, transparent, and without spicules; it rests on the skeleton, and is pierced by the ends of the 

 fibres, so that no particular dermal skeleton is found. The colour (in spirit) is dirtily grayish yellow. 

 The whole sponge is filled with sand to a high degree, what has, perhaps, taken place in the trawl. 

 The features of this sponge with regard to oscula and pores seem to be the same as those, supposed 

 to be found in the preceding species. Pores are found in large numbers on both sides, they have 

 been measured to a size of from ca. 0-05 — 0-17"'". In the skeleton oscular canals are found, somewhat 

 .smaller than in the preceding species, viz. ca. 0-5'""'; they are very close to each other, and go 

 horizontally almost quite through the sponge. These oscular canals open on one side of the sponge 

 with apertures that are seen to be rather well bounded in the skeleton; the apertures are of the same 

 diameter as the oscular canals; but as I have seen no osculum distinctly bounded by the dermal 

 membrane, I cannot give the real size of the oscular aperture; the whole structure implies, however, 

 that the osculum formed by the skeleton, is not narrowed by the dermal membrane. The projecting 

 spicules that are situated on the margin of the osculum, project partly over it, in such a way as 

 pictured in the following species. Thus oscula are only found on one side of the sponge; to be sure 

 similar openings may be seen here and there on the other side, but then they seem to be due to a 

 damaging of the surface, so that this has been broken through to the oscular canal. 



The skeleton of this species is constructed in quite the same way as that of the preceding one, 

 and here are also found irregularly running, polyspicular longitudinal fibres; these may, on their way 

 upward, bend out towards the sides, and thus they may go in directions very different from that of 

 the longitudinal axis. The ends of the spicules are as usual united by spongin. 



Spicula are oxea, evenly and rather gradually tapering; they are slightly curved, sometimes 

 almost straight. The length is very constant, between 0-19 og 0-21"™, but is most frequently 0-208"""; 

 also the thickness is constant, 0-013 — 0-014™"'. Shorter and finer spicules are only seen quite singh-. 



Locality: Station 46, 61^32' Lat. N., ii'^36' Long. W., depth 720 fathoms; station 21, 58°oi' Lat. N., 

 y '^"^O"'*- \ 44° 45' Long. W., depth 1330 fathoms, a very small fragment. 



■,-'\ 

 > r—j 4. R. ventilabrum Frstdt. 



PI. XI, Figs. 6-7. 

 1887. Reniera ventilabrum Fristedt, Vega Exp. vetensk. lakttag. IV 420, PI. 24, fig. 3, PL 27, fig. 8. 



Erect, leaf- or fan-shaped. The dermal »iembrane thin, tvithotd spicules; the ends of the fibres 

 project, and so the surface is finely shaggy. Oscula numerous, small, only found on one side. The ske- 

 leton is a regular network of primary and secondary fibres ; the fibres unispicular. Particular polyspicular 

 fibres issieing from the base and running longitudinally, are found in large numbers. Spicula are evenly 

 tapering, slightly curved oxea 0-21 — 0.2^""". 



Of this sponge we have a specimen, which is all but fanshaped, increasing in breadth upward 

 from a base that seems to have been a short stalk. The somewhat damaged specimen has a height 

 of ca. i8<='" by a greatest breath of ca. 15'='", the thickness is ca. 4""". The consistency is rather fragile, 

 only the base is considerably harder on account of the numerous longitudinal fibres. Here and there 

 the surface shows slight depressions, but is otherwise even, and everywhere finely shaggy from the 



