!gO PORIFERA. II. 



It may, in a few cases, continue far down the style The length of the styli is 0-46— o-536'" m , and the 

 thickness 0-0078 — o-on mm . 2. The dermal spicules are straight or somewhat curved tylota; their 

 length is 0-34—0-38""" and the thickness ca. 0-0044"""; one end is always somewhat thinner than the 

 other, and the swelling of this thinner end is more distinctly marked, being as large as that of the 

 opposite end. b. Microsclera; these are isancorse unguiferse and bixotulse. 1. The an corse are of a 

 similar form as in the preceding species, but the teeth are comparatively longer; they have seven to 

 nine free teeth, and one or two teeth united with the shaft. Their length is 0-038— o-050 mm , and the 

 thickness of the shaft is 0-0037 — 0-0050" 1II \ 2. Birotulse have eleven to fourteen teeth at either end; 

 their length is o-oi8— 0-02 i mm , quite few reached a length of o - 028 min , the thickness of the shaft is 

 ca. o-ooi3 ram , the breadth across the circle of teeth is 0-0057— 0-007 mm . The microscleres occur through- 

 out the sponge, the aneoree are numerous in the dermal membrane; birotulse are found in predominant 

 numbers. 



Locality: Station 93, the Denmark Strait, 64°24' Lat. N., 35" 14 Long. W., depth 767 fathoms. 



5. I. intermedia 11. sp. 

 PL XVIII, Fig. 5 a— d. 



Incrusting. The surface smooth. Tlic dermal membrane a thin film, supported by recumbent 

 bundles of dermal spicules. The skeleton chiefly consisting of irregularly placed spicules and spicula- 

 bu 11 dies. Spicnla : Mcgasclcra : the skeletal spicules styli crjj? — 0-48""". the dermal spicules tylota 0-26 

 — o-j4"""; microsclera of tivo forms, isancorc unguiferce zvith nine to eleven free teeth 0-040 — o'ojo""". 

 birofuhr with fourteen to fifteen teeth o-oi8 — 0-021""". 



We have only one specimen, forming a longish, irregular incrustation on a Homcra lichenoides; 

 the length of the sponge is 17""", and the thickness does not exceed 2" ,m . The colour (in spirit) is a 

 dark grayish brown. The surface seems to be smooth. The dermal, membrane is a thin film, supported 

 by bundles of dermal spicules. Pores and oscttla were not seen. 



The skeleton. The dermal skeleton consists of penicillate bundles of dermal spicules, projecting 

 and supporting the dermal membrane. The bundles seem always to be highly recumbent. The main 

 skeleton, as far as I have been able to examine it, consists of irregularly placed spicules and spicula- 

 buudles. It appears that short, loose fibres may be formed, but a net of meshes is not formed. A 

 slight amount of spongiu is found where the spicules are united. 



Spicnla: a. Mcgasclera. 1. The skeletal spicules are styli; they have a slight curve at 

 the upper end, else they are straight; they are almost not tapering, and the point is short or rather 

 short. The upper end is very frequenth' distinctly the thickest part of the style. Their length is 

 0-357 — ovL8 mm and the thickness o-oio — o-oi3 mm . 2. The dermal spicules are tylota; they are straight 

 and are not thicker in the middle. Their length is 0-26— 0-34'"'" and the thickness 0-0050—0-0064""". 

 One end is always a little thinner than the other, b. Microsclera ; these are isancorse unguiferae and 

 birotulse. 1. The an corse are of about the same form as in dubia; they have nine to eleven free 

 teeth, and one or two teeth united with the shaft; their length is 0-040 — 0-050""", and the thickness of 

 the shaft is o-oo4 mm . 2. Birotulae; their number of teeth seems to be more constant than in the 



