PORIFERA. III. 



particles of the substratum; the spicules situated here may be directed in any direction. At the sub- 

 stratum there is a small amount of spongin. 



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

 groups, large and small; the large styli are rather long and slender, they are straight or slightly and evenly 

 curved; the head is weakly or not at all developed; they taper only a little outwards, and they are short and 

 abruptly pointed. The spinulation is only present in the lower part of the style, at most stretching 

 half the way out, but very dispersed in the outer part; the spines are somewhat robust, generally 

 there are some larger spines among them, especially at or near the base, thus marking the otherwise 

 weakly marked head. The small styli do not reach more than one fourth in length of the large, they 

 are straight and longer pointed than the large; their spinulation resembles that on the base of the 

 large, but they are spined in their whole length. The large styli are 0-35 0-63 mm long, and the 

 diameter at the base is 0-020 0-028""". The small styli are of a length of 0-13 o'lyS" 1 " 1 and a diameter 

 at the base of about 0-014 mm . No intermediate forms between the two sizes of the styli are found. 

 2. The dermal spicules are long and straight strongyla; one end is generally a little thinner than 

 the other, but otherwise they are nearly of the same thickness throughout their whole length. The 

 length is 0-35 O'52 mm and the diameter o - oo6 o - oo8 mm . b. Microsclera. These are chelae arcuatse, 

 they have an evenly curved shaft, the alae are strongly incised in the lower edge, and hence somewhat 

 claw-shaped when viewed laterally, the tooth is pointed lanceolate. The length of the chelae is 

 0-038- 0-050"""; the shaft is somewhat flat, the thickness is in relation to this 0-004 0-007 mm . The 

 chelae are seen in small numbers through the whole sponge and densely filling the dermal membrane. 



This species is somewhat related to H. nummulus, but it is, as mentioned under this species, 

 distinguished by smaller acanthostyli and a different shape of the chelae. 



Locality: Station 113, 69 31' L,at. N., 7 06' Long. W., between Iceland and Jan Mayen, depth 

 1309 fathoms (bottom temperature -7- ioC); about ten specimens. 



14. H. verrucosa n. sp. 

 PI. Ill, Fig. 3. PI. VII, Fig. i. 



Incrusting; thickness about 2"""; surface smooth, covered with loart-shaped papilla with a dense 

 skeleton of dermal spicules in the wall, bearing oscula (and pores). Dermal skeleton strongly developed, 

 the main skeleton weak. Spicula: megasclera; the skeletal spicules acanthostyli with a generally small 

 head, the longer only spined below, the smaller spined in the whole length, 0-093 0-6 2 mm , not divided 

 into two groups; the dermal spicules long strongyla o-j? 0-52"""; microsclera chela- arcuatte o-ojj 



Of this species we have four specimens, one has grown as an incrustation on a stone from which 

 it has been peeled, in the basal part of it much gravel and the like is imbedded; the specimen is 

 now separated into two pieces of a largest extent of about 25""", but they have certainly formed a 

 single incrustation. Of the other specimens one forms an incrustation on a basalt-block, it has a 

 greatest extent of 22 ram ; two others cover Astar(c-s\iz\\s and are of similar dimensions. The thickness 

 is about 2 nim . The colour is in the present state (in spirit) greenish white, but for one of the speci- 

 mens it is stated to have been deep blue in the fresh state of the sponge. The surface is smooth, 



