PORIFERA. III. 



This chela bears, in its mostly curved forms, strange to say, great resemblance to the chela 

 found in a species standing rather remote, viz. the chela figured by Carter (Ann. Mag. Nat. Hist 5, 

 XV, PL IV, figs. 36, f.). Carter figures also a developmental stage (d), but considers this as an "ill- 

 developed" spiculum. 



Locality: Station 15, 66 18' Lat. N., 25 29' Long. W., depth 330 fathoms (bottom temperature 

 4-o75C.); station 89, 64 45' Lat. N., 27 20' Long. W., depth 310 fathoms; both these localities lie in 

 the Denmark Strait; further it was taken East of the Faroe Islands, depth about 250 fathoms, and 

 West of the Faroe Islands, depth 160 fathoms, (Ad. Jensen, the cruise of "M. Sars" 1902). Four speci- 

 mens in all. It is curious that one of the localities, station 15, shows a negative bottom temperature, 

 while the other localities are positive, but it is to be remarked, that this station lies just at the border 

 between the cold and the warm areas. 



7. H. rugosa n. sp. 

 PI. Ill, Fig. i, PI. VI, Fig. 3. 



Incrusting ; surface somewhat wrinkled, smooth; oscula present as very low cones, -with a dense 

 skeleton of dermal spicules in the wall. Spicula: megasclera; the skeletal spictiles acanthostyli -with a 

 slight head, spined in the whole length, divided into two groups, large o-jo 0-429""*, small 0-15 ovp""",- 

 the dermal spicules polytylote strongyla 0-31 0-417"""; microsclera large chela arcuatce with the ends a 

 little recurved, o - oj2 o- 



Of this species we have two specimens, one growing on a Brachiopod-shell, the other on a 

 worm-tube. The sponge forms thin incrustations, which reach a greatest extent of 17 mm , with a thickness 

 not exceeding 0-5 mm . The colour (in spirit) is yellow or light brownish. The surface is strongly 

 wrinkled and rugose, the dermal membrane being folded, thus giving rise to the formation of irregular, 

 sinuous furrows; this appearance is probably owing to contraction; for the rest the surface is smooth 

 without projecting spicules. The dermal membrane is a somewhat solid, easily separable membrane, 

 richly crowded with chelae. On one of the specimens two oscula are seen; these have a structure 

 similar to that of the oscula in H. Koehleri, they show in the centre a circular or oval impression, 

 around which the dermal membrane forms stellately radiating folds; the dermal spicules form here a 

 special skeleton, lying close together in the oscular wall with one end towards the opening, and from 

 this radiating out in the membrane. The diameter of that part of the membrane which may be 

 termed osculum is 1*5 2 mm . Pores were not to be seen in the membrane which is so densely charged 

 with chelae. 



The skeleton. The dermal skeleton; the dermal skeleton proper is formed of the chelae which 

 are extremely close-lying in the membrane; when they are so close-lying, this is perhaps due to 

 contraction. The dermal spicules partly contribute to the formation of the other skeleton of the 

 sponge, as they form bundles or fibres, stretching from the very base up to the dermal membrane, 

 generally in a very oblique direction; in many places they also form horizontal fibres just below the 

 membrane; finally they form, as mentioned, the skeleton in the oscular wall. The fibres and bundles 

 formed of the dermal spicules are rather thick. The main skeleton is of the typical construction, and 



