PORIFERA. I. 



15 



Locality. Jakobshavn in Greenland, one specimen, depth unknown (Pfaff). 



Geogr. dtstrib. Fristedt gives two specimens from Bohuslan, depth ca. 90 fathoms (175 metres). 



2. S. moUicula n. sp. 

 PI. VIII, Figs. 12-14. 

 0/(1 soinezvhat irrcgnlay form co)/ si sting of a steni^ from the ends oj zvhich tubes issue. The 

 fibres form a regular skcletoii of longitudinal fibres (running towards the surface) and transverse 

 fibres^ the meshes are quadratic^ rectangular^ or polygonal. By far the greatest part of the fibres uni- 

 spicular, only sometimes ivith a couple of spicules. Only little spongin. Particular longitudinal fibres 

 xvanting. The surface finely shaggy from projecting spicules. Each tube ends tvith an osculuin. .Spi- 

 cula oxea somezvhat curved, o-ij—o-ifS""". 



The only specimen in hand of this species has a somewhat irregular form; it is in two places 

 fastened to pieces of laminarian fronds, and from here originates on one side a cylindric stem, dividing 

 into two branches each ending with an osculum; on the other side of the fastening two shorter tubes 

 issue. The principal stem seems to have been lying more or less horizontally, while the tubes have 

 risen more or less verticalh- from the stem. The total length of the specimen is ca. 60""", and the 

 diameter of the stem 10 — la""'". The colour (in spirit) is light brown. The consistency is very soft, 

 but elastic. The surface is finely shagg)' from projecting spicules. The dermal membrajie is thin 

 and transparent, and rests on the skeleton below. Each tube ends with an osculum of a diameter of 

 2 — 2'"™; the ends of the tubes are rounded, and accordingly the edges of the oscula are not sharp. 

 The osculum leads into an oscular canal of the same diameter, and the oscular canals of the tubes 

 are continuations of the canal of the stem. As far as I have been able to decide, the canals run from 

 the surface obliquely upward and inward as in the preceding species, and the excurrent canals open 

 into the oscular tube. The pores are found in great numbers and very close together in the dermal 

 membrane, often reducing this to a reticular work; most frequentl}- the}- are round; their sizes have 

 been measured to 003 — o-i8""""). 



The skeleton is of quite the same structure as in the preceding species; accordingly it consists 

 of primary fibres running from the wall of the oscular tube in a curved manner upward and outward 

 to the surface; these fibres are connected by transverse spicules mostly single or only forming incom- 

 plete fibres. The net is rather regular, and the meshes quadratic, rectangular, or polygonal. The 

 distance between the primary fibres may be somewhat varying; most frequently it is equal to the length 

 of a spicule, or o'i2'"'", but it may be considerably greater, up to 0-23'"'", and upon the whole the ske- 

 leton is more open than in the preceding species; its regular structure is distinctly seen in the tubes, 

 but is far less marked in the stem. The skeleton is almost exclusively unispicular, some of the pri- 

 mary fibres may, however, be composed of a few spicules in their whole course or part of it; jDolyspi- 

 cular longitudinal fibres as in the preceding species, are not found here. In spite of the soft consist- 

 ency of the sponge the spongin is comparatively more developed than in the preceding species, it is 



' I This species shows a particular structure, which I have not been able quite to interpret ; besides primary fibres 

 projecting through the dermal membrane, there are also here found transverse spicules, so that we get a net of spicules out- 

 side of the dermal membrane. This peculiarity may perhaps be due to contraction on account of the sponge ha\-ing been 

 kept in spirit; it is also possible that the real dermal membrane has been lost. 



