PORIFERA. III. 65 



divided into two groups, large, only spincd at the base, 0-42 .0-59""", small, entirely spined, o-og o-2j mm ; 

 //if dermal spicules large tomato., 0-32 o'$o mm ; microselera small chela' arcuatce, resembling palmate 

 chela", 0-0.25 o-ojo""". 



The only specimen of this species forms an incrustation on a shell of a Brachiopod; it has a 

 greatest extent of about 15"""; the thickness is 0-5 mm or a little more. The colour (in spirit) is dark 

 brownish. The surface is smooth or nearly so, without projecting spicules; it bears some conical 

 papillae of a length of about i mm ; in the present state of the sponge the papillae are lying down to- 

 wards the surface. The dermal membrane is thin, resting on the skeleton beneath and provided with 

 some spicules, more or less scattered or bundle-like collected. Oscula and pores: the mentioned papilla? 

 are oscular papillae with the oscular opening at their apex; the fibres of dermal spicules continue into 

 the wall of the papillae and form here a dense skeleton of spicules lying parallel to the longitudinal 

 axis of the papilla; pores were not observed with certainty; some few, small openings in the dermal 

 membrane may perhaps be pores. 



The skeleton. The dermal skeleton. The skeleton formed of the dermal spicules consists of 

 bundles or short fibres, which stretch from the lower part of the sponge up to the dermal membrane; 

 the fibres are for the greatest part more or less horizontal; some single spicules or bundles lie in the 

 membrane or just below it. The main skeleton is in the ordinary way constructed of perpendicular 

 acanthostyli with the heads against the substratum; they are not close-standing but somewhat 

 scattered. A very slight amount of spongin is present at the heads of the acanthostyli. 



Spicula: a. Megasclera. i. The skeletal spicules are acanthostyli; they are straight or 

 slightly curved near the base, and long pointed; the head is more or less pronounced, but generally 

 only to a slight degree. The longer styli are only spined at the base, on the head and a little way 

 out; the small styli are entirely spined, but the spines become scattered towards the point; the spines 

 are small, only at the base some few spines a little larger may be found. The styli are divided into 

 two distinctly separated groups, large and small; the large has a length of 0-42 o'59 mm and a diameter 

 of the head of 0-021 0-02 5"""; the small styli are 0-09 0-23 mra long, and the diameter of the head is 

 0-014 0-02 1 mm . 2. The dermal spicules are rather large tornota, they are straight or nearly so, 

 slightly tapering towards the ends and sometimes slightly polytylote; the points are short and sharp, 

 sometimes the ends are a little swollen; the length is 0-32 O'5O mm and the diameter is 0-004 0-007 mm . 

 b. Microselera; these are chelae arcuatse; they are small and slender, the shaft is only slightly 

 curved, the tooth is elliptical; the alae are connected with the shaft for about their whole length and 

 the chela thus greatly resembles a palmate chela, or might perhaps even be termed so; the length 

 of the chela is 0-025 0-030"' an d the thickness of the shaft 0-002 """. The chelae are seen singly in 

 the tissue, and they occur in rather great numbers in the dermal membrane, but they form no layer. 



This species is nearly related to //. platychela and has similar large dermal tornota, but it 

 differs by the much less spined styli and the small chelae, which are quite different in shape, and 

 finally also by the oscular papillae. 



Locality: Station 28, the Davis Strait 65 14' Lat. N., 55 42' Long. W., depth 420 fathoms. One 

 specimen. 



Thi- Ingolf.Ripcdilion. VI. 3. 9 



