i 9 4 



PORIFERA. II. 



Locality : The Ingolf, station i, 62 30' Lat. N., 8° 21' Long. W., depth 132 fathoms, two specimens; 

 62° 29' Lat. N., 5 C 17' Long. W., depth 160 fathoms (Ad. Jensen, the cruise of the Michael Sars ■> 1902), 

 one specimen; 66° 54' Lat. N., I5°35' Long. W., depth 58 fathoms (H. M.S. Beskytteren Gemzoe), one 

 specimen. The localities are situated at the Faroe Islands and north of Iceland. 



8. I. affinis n. sp. 

 PI. XVIII, Fig.8a-e. 



The form massive, somewhat erect? The dermal membrane a thin film, supported by bundles 

 and short fibres of dermal spicules. The skeleton an irregular, polyspicular reticulation. Spicula: 

 Megasclera: the skeletal spicules styli ortf — 0-5 ;■""". the dermal spicules tylota o-jj — 0-44"""; microsclera 

 two forms of birolutcr, large ones zvith nine to thirteen teeth 0-037 — o-oj/""", small ones with eleven to 

 fifteen teeth o-o/S— 0-023""". 



( )f this species we have one highly damaged specimen. To judge from this, the sponge seems 

 to have been erect, I suppose, of about a thick, irregular cylindric form. The height is ca. 70'"'" and 

 the thickness ca. 50"™. The colour (in spirit) is grayish brown. The consistency is exceedingly loose 

 and brittle, to which the bad state of preservation may partly be owing. Of the dermal membrane 

 only a few fragments 011 the upper surface of the sponge are preserved; it is a rather thin film, 

 showing here pores and oscula. The pores are gathered in groiips; the}' are about circular, their size 

 was measured to between 0^03 and o - 24' mn . Oscula are scattered between the pores; they are also 

 circular, of a size of ca. o^" 1 "'. 



The skeleton. The dermal skeleton is formed in the usual way by dermal spicules partly 

 forming erect bundles, partly passing under the membrane as fibres from which spicules project. The 

 main skeleton is a chiefly polyspicular, quite irregular reticulation; meshes are formed, but they are 

 quite irregular; longer fibres do not seem to be formed, or are only formed to a small degree; in 

 sections, however, a tendency is seen towards fibres passing in the longitudinal direction, but they are 

 generally rather short. In a few places the skeleton appears to be a little more regular. A distinct, 

 but clear and white mass of spongin is found where the spicules are united. The sponge embodies 

 sand and gravel to a rather high degree. The skeletal structure in this species seems, with regard 

 to development, to occupy a position between the incrusting or massive species and a leaf-shaped 

 species as the polydeutata described above. 



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

 not rarely a little irregularly; the curve is most frequently situated nearest to the head-end. They 

 are only little tapering outward, and the point itself is rather short. Their length is 0-47 — o - 57 mm , and 

 the thickness is ca. o - on — o-oi5 ram . A few developmental forms were seen. 2. The dermal spicules 

 are tylota; their ends are more or less, most frequently rather slightly, swollen; the tylota are straight 

 or quite slightly curved. Their length is 0-35— o\44 mm , and the thickness is ca. 0-0035- -o-oo57 mm . There 

 is, as usual, a little difference between the two ends of the tylota, the shaft being somewhat thinner 

 in one end than in the other, and this feature is the more marked, the younger the spicule is. 

 b. Microsclera; these are birotuhe of two sizes. 1. The large birotulte have at either end nine to 



