PORIFERA. II. 



149 



the two others to living specimens of an ^f/rrt-species. The colour (in spirit) is light brownish. The 

 consistency is rather soft, but somewhat elastic. The surface, as far as I have been able to observe, 

 is slightlv shaggy when undamaged; in many places in the specimens in hand it is more shaggy, the 

 ends of primary fibres projecting, but this, I think, is only due to damaging. The dermal membrane 

 is a thin film, mostlv supported by bundles of dermal spicules. Pores and oscula were not observed. 



The skeleton. The derma! skeleton, as far as I have been able to see, consists of bundles or 

 short fibres of dermal spicules, issuing from the skeleton and supporting the dermal membrane; this 

 membrane, however, has also in places horizontal, scattered spicules, and, besides, it is highly filled with 

 microscleres. The primary fibres of the skeleton pass perhaps also in places quite to the surface. The 

 main skeleton consists of primary longitudinal fibres, passing from the stalk up through the sponge, 

 branching and bending to all sides towards the surface. These fibres are polyspicular and powerful, 

 and in the lower part of the sponge, above the stalk, they may be o-25 mm thick; upward and outward 

 they become thinner. Regular secondary fibres are not formed, but between the longitudinal fibres are 

 found partly transverse spicula-bundles, partly single transverse spicules, placed more or less irregularly. 

 A distinct, but clear and little conspicuous mass of spongin is found. It is especially visible in the 

 nodes, but it may also often be seen to coat the longitudinal fibres with a very thin layer. Down in 

 the stalk the spongin is more copious and of a yellowish colour. 



Spicula: a. Megasclera. 1. The skeletal spicules are smooth styli; they are somewhat 

 curved, most frequently nearest to the head-end, more rarely they are straight. They taper evenly to 

 an about middle long point. Their length varies from 0-36 — cr50 mm , and the thickness is in proportion 

 0-014 — o - 02i mm . Quite few finer developmental forms were seen. 2. The dermal spicules are 

 tornota; thev are cvlindric and straight, or more rarely quite slightly curved. In the form of their 

 ends they are most similar to the tornota in M. Jimbriata, the ends being rather stubby, but with a 

 little mucro at the apex. Generally one end is a little thicker than the other. Their length is 0-238 

 — o-34 mm , and the thickness is 0-007 — croo8 mm . Developmental forms with one end quite pointed were 

 found quite singly, b. Mierosclera; these are of only one form, three-toothed isancorse spatuliferse. 

 These ancorse are of a similar form as the large ancorae in the preceding species; the teeth are most 

 frequently broadlv rounded at the end, and narrow alse are found of the same length as the teeth. 

 The length of the ancorae is between 0-054 and o-o66 mm , and the thickness of the shaft is ca. 0-005 — 

 o-oo/"" 11 . The ancoree occur throughout the tissue, but are especially numerous in the dermal membrane. 



Embryos. In one specimen embryos were found; they were scattered in the tissue and were 

 easily distinguished by their dark, yellowish red coiour. They are globular, of an average diameter 

 of o-26 mm . Most of the specimens examined showed no spicules, or only a few small styli which would 

 thus seem to be first appearing. One of the embryos, on the other hand, had both megascleres and 

 microscleres. The megascleres are small subtylostyli, they are not smooth, but spiried or rugged. 

 The microscleres were developmental forms of the ancora, they were smaller than in the developed 

 sponge, only ca. o-035 mm long. The specimen in question was obtained towards the close of July. 



Locality: Station 2, 63 04' Lat. N., 8° 21' Long. W., depth 262 fathoms, one fragment; station 116, 

 70° 05' Lat. N., 8° 26' Long. W., depth 371 fathoms (bottom temperature -f-o°4C), two specimens. Of 

 the localities one is situated south of Jan Mayen, the other between Iceland and the Faroe Islands. 





