8 4 



PORIFERA. III. 



spicules liere forming fibres which run stellately to the top or the middle of the cone, but also here 

 the fibres run below the dermal membrane and not in it, and the dense layer of chelse continues just 

 to the centre of the cone. The main skeleton consists in the ordinary way of perpendicular acantho- 

 styli with their heads on the substratum; the longest styli reach up to the dermal membrane. At the 

 base a small amount of spongin is present. 



Spicula : a. Megasclera. i. The skeletal spicules are acanthostyli; they are slightly curved, 

 generally nearest the base, and they are somewhat densely spined in their whole length; the head is 

 round and generally well marked; the spines on the head are straightly radiating, on the shaft they 

 are reclined. The spicules vary much in length, but as all intermediate sizes are present they are 

 not divided into two groups; the length is o - i2 — 0*38 mm and the diameter of the head 0-02 — 0-03 mm . 

 2. The dermal spicules are straight and very slightly fusiform; they may be termed subtoruota, 

 but generally one end is rounded so that they are tornostrongyla and also both ends may be rounded, 

 the spicules thus being strongyla; they are distinctly polytylote. The length is 0-27— o - 38 mm and the 

 diameter croo6— o - oo8 mra . b. Microsclera are chelse arena tee of a very characteristic and remarkable 

 shape; the shaft is very strongly curved, sometimes to so high a degree that its end-parts form two 

 nearly parallel arms; on the middle of the hinder side of the shaft there are a number of strong 

 spines. Also the shape of the end-parts of the chela affords great interest; the tooth is protruding 

 greatly forwards, but it is formed almost entirely of the strongly developed falx, while there is nearly no 

 plate, the falx only being somewhat thickened at the front edge; the alse are also very interesting, 

 they quite resemble the falx in shape and they are of the same size, further they are directed straight 

 out to each side, so that they form right angles with the falx, on the other hand they are not or 

 almost not bent forwards. The whole construction of the end-parts recalls the construction characteristic 

 for the ancorse, but I shall otherwise draw no conclusion from this fact at present. The chelse are 

 nearly always somewhat coutorted. Same few developmental stages were seen, they show spines on 

 the shaft already when rather thin. The length of the chela, which is somewhat dependent on the 

 degree of the curvature, is 0-031 — 0-043 mm , anc ^ tne diameter of the shaft, the spines not included, is 

 0-005— 0-007 mm . As mentioned the chelae form a dense layer in the dermal membrane, but they are 

 also seen in the other parts of the sponge. 



Locality: Station 9, 64 iS' Lat. N., 2J° 00' Long.W., depth 295 fathoms; station 81, 6i° 44'Lat. N., 

 27°oo' Long. W., depth 485 fathoms; station 85, 63 21' Lat. N., 25 21' Long. W., depth 170 fathoms; 

 station 98, 65° 38' Lat. N., 26 27' Long.W., depth 138 fathoms; further it has been taken at 65 50' Lat. N., 

 26 53' Long. W., depth 208 fathoms (The Fishery investigation steamer "Thor"), and West of the Faroe 

 Islands in depths of 160 and 180 fathoms (Ad. Jensen, the cruise of "M. Sars" 1902). In all about ten 

 specimens. The localities lie in the Denmark Strait and West of the Faroe Islands. 



Geogr.distr. Schmidt had the species from South-west of Bukeufjord, Norway, depth 106 fathoms. 



33. H. aenigma n. sp. 



PI. IX, Fig. 1. 

 Incrushng; surface for the most part hispid, tvith some conical projections , bearing oscular 

 Spicula: megasclera; the skeletal spicules acanthostyli with no real head-swelling, they are entirely 



