74 



PORIFERA. III. 



25. H. bractea n. sp. 

 PI, VIII, Fig. 3. 



Incrusting; surface hispid. Spicula: megasclera; the skeletal spicules acanthostyli, divided into t^vo 

 groups, large, -with a small head, only spined in the lower part, 0-280-36""", small, without head, entirely 

 spined, 0-12 0-15""*; the dermal spicules tylota o-2j 0-50 ""*/ microsclera chel(e arcuata 0-028 0-034""". 



Of this species we have only a very small specimen, and the description will therefore in some 

 respects not be quite satisfactory. The specimen grows on a Brachiopod-shell together with a specimen 

 of Hymenancora diiplicata n. g. et sp. (to be described hereafter), and a small specimen of Melonanchora 

 emphysema. It forms a very small, almost circular incrustation, scarcely two millimeters in diameter 

 and very thin; it bears about in the middle a low, cylindrical papilla. The colour (in spirit) is greyish, 

 and the sponge is somewhat transparent. The surface is in the present state hispid from projecting 

 skeletal styli. About the dermal membrane I can say nothing, and also nothing about pores and oscula; 

 probably the papilla mentioned is an osculum, but I could not observe it. 



The skeleton. The dermal skeleton seems to consist of scattered bundles of dermal spicules, 

 and it is, so far as I could observe, relatively weakly developed. The main skeleton is constructed in 

 the ordinary way and consists of vertical acanthostyli with their heads on the substratum, and it is 

 somewhat dense; the longest of the acanthostyli project beyond the surface, and it seems to be so 

 also in the undamaged sponge. 



Spicula: a. Megasclera. i. The skeletal spicules are acanthostyli which are divided into 

 two groups, large and small. The large acanthostyli are straight, they have a small head-swelling 

 and taper evenly into a long apex which is a little more abruptly pointed outermost; they are spined 

 only on the basal part, at most on the half part; the spines are of medium size, largest below; they 

 are placed most densely on the head-swelling, but more dispersed outwards. The small styli have no 

 head-swelling; the base is the thickest part and from here they taper evenly to the point, thus as- 

 suming a club-like shape; these styli are spined in their whole length, the spines at the base radiate 

 straight out, those on the shaft are reclined. The length of the large styli is 0-28 0-36 rom , and the 

 diameter of the head is about o - o2 mm ; the length of the small styli is 0-12 cri5 mm with a diameter at 

 the base of o-oi4 mra . 2. The dermal spicules are straight and somewhat slender tylota, the end- 

 swellings are distinct but not large; the length varies rather considerably, from 0-27 o'5o mra , and the 

 diameter of the shaft is 0-004 0-007 mm . b- Microsclera ; these are chelae arcuatse, they have a curved 

 shaft, elliptical teeth and lobe-shaped but somewhat narrow alse. The length of the chela is 0-028 

 0-034 mm , and the diameter of the shaft 0-004 0-005 rara . The chelae seem to occur through the whole 

 tissue, but are seen especially at the surface. 



Locality: Station 89, The Denmark Strait, 64 45' L,at. N., 27 20' Long. W, depth 310 fathoms. 



26. H. laevistylus n. sp. 



PI. VIII, Fig. 4. 



Incrusting. Spicula: megasclera; the skeletal spicules acanthostyli -with a very small head, only 

 spined on and just at the head, for the rest smooth, -very uniform in size, 0-44 0-48"""; the dermal 

 spicules tylota varying to strongyla, 0-27 0-34"""; microsclera chela 1 arcuatcr 0-045 0-052""*. 



