20 PORIFERA. III. 



distributed in the Atlantic Ocean together with the Denmark and Davis Straits between 66 35' and 

 38 31' Lat N., and with a bathymetrical range from 106 to 485 fathoms. For the specimens from the 

 Norwegian North-Atlantic Exp. no particular locality is known. 



2. I. viridis Tops. 

 PL II, Figs. 1 1- 12, PL IV, Fig. 7. 



1892. Joyeuxia viridis Topsent, Resultats des camp, scient. du Prince de Monaco, Fasc. II, 94, PL II, fig. 8, 

 PL X, fig. 19. 



Erect, somewhat club-shaped, or of a lower and somewhat semiglobular shape; there are more or 



less numerous papilla in the upper part. Surface smooth. Outermost there is a solid dermal layer. 



Oscula and pores each at the summit of their own papilla. The dermal skeleton formed of close-lying 



tangential spicules in several layers; the inner skeleton consisting of bundles and thin fibres running 



parallel -with the surface, withotit transverse fibres. Spicula: Megasclera strongyla 0-66 no""", 



This species differs from the preceding one externally in being considerably larger and 

 in having no peduncle. Of the specimens in my material only three are tolerably entire; of these 

 the two are erect and somewhat clnb-shaped, being a little narrowed below, the third is lower and 

 relatively broader. Above, the sponge has more or less numerous conical papillae; below, it has been 

 attached, and it would seem as if it had grown on the bottom itself, the base of attachment being 

 beset with gravel and other small particles. The largest of the entire specimens has a height of 

 30"', and a breadth of about i8 mm , and at the base a breadth of fully io mm ; another specimen of a 

 similar shape is somewhat smaller; the lower and broader specimen has a height of about 20 mni 

 with a breadth of about 15""". The colour is (in spirit) light brownish yellow or olive; the colour of 

 the inner body is deeper than that of the dermal layer. The consistency is bladdery, the outer 

 layer hard and firm, the inner body brittle and soft The surface is smooth. The dermal layer is 

 provided with tangential spicules in several layers, and it is somewhat thicker than in /. pellicula and 

 reaches a thickness of about 0-5 mm , in places even more. Oscula xn& pores: the papillae mentioned are 

 partly oscular and partly pore-papillae. The oscular papillae are conical, of a height of 3'"'", but they 

 may contract themselves and are then quite low. When they are open the osculum is a simple opening 

 at the summit In the wall of the papillae the spicules are close-lying; they do not lie, however, in the 

 longitudinal direction but in two directions crossing each other almost rectangularly and both obliquely 

 to the longitudinal axis of the papilla; when the papilla is quite extended the two sets of spicules 

 are arranged in rather distinct, but close-lying bands, btit when the papilla is contracted and the 

 osculum closed the spicules form a compact mass and when the papilla is then examined from the 

 end the ends of the close-lying spicules are seen. The pore-papillae are of another construction and 

 easily distinguishable from the oscular papillae; they are larger, especially broader, and they are not 

 conical but cylindrical; they are generally placed on the sides of the upper part of the sponge, and 

 they are not directed straight outwards but somewhat upwards so that their opening points upwards, 

 they are at the same time somewhat adpressed in towards the sponge and hence elliptical in circum- 

 ference; they have a breadth of 6 io mm ; on account of the manner in which they are attached, their 



