g 2 PORIFERA. III. 



in the small than in the large styli. 2. The dermal spicules are tylota, they are straight or 

 generally slightly and somewhat irregularly curved, often with a curvature recalling to some degree 

 that found in the dermal spicules of H.filifera; the end-swellings are small, sometimes almost dis- 

 appearing; the length is 029— 0-38""" and the diameter 0-004— 0-007 mm . D - Microsclera are of two forms, 

 chelae arcuatse and sigmata. 1. The chelae have a curved shaft the free middle part of which is 

 more than one third of the length, the alae are lobe-shaped, their lower margin not much incised; the 

 tooth is narrowly elliptical; the length is 0034 — 0*042 mm and the diameter of the shaft about 0-003 """• 

 2. The sigmata are of common shape, but they are quite or nearly quite plane; the length is not 

 very variable 0-58—075'"'", generally nearest the latter size; they are relatively thin, the thickness 

 being 0.0028""". As far as I have been able to ascertain, both chelae and sigmata occur through the 

 tissue, while in the dermal membrane only the chelae occur, but here in great numbers, and in places 

 King densely. Of the microsclera the chelae are the most numerous. 



This species is distinguished from grandis and digitata by its plane, thin sigmata and besides 

 by characters in the other spicules. 



Locality: Station 85, the Denmark Strait, 63 21' Lat. N., 25 21' Long. W., depth 170 fathoms. 

 One specimen. 



38. H. macrosigma 11. sp. 

 PL IX, Fig. 6. 



In crusting; surface smooth. Spicula : megasclera ; the skeletal spicules acanthostyli with a small 

 head-swelling, spined in the whole length, but the spines much dispersed outwards, o-ij — 0-28""", not 

 divided into two groups ; the dermal spicules strongyla or subtylota 0-23—0-28"""; microsclera three forms, 

 chela- arcuatce 0-020— 0-032""". sigmata of two forms, large 0-18 — 0-208, small 0-06— 0-089""". 



We have three specimens of this species, one of them grows on aggregated sponge-spicules; it 

 incrusts these all round, so that they are chiefly situated in the interior of the sponge, but stretching 

 out here and there. Of the other two specimens one grows on a Brachiopod-shell, the other on a 

 basalt block. The specimens are rather small, one only about 8 mm , the others 12'"'" in greatest extent. 

 The colour (in spirit) is yellowish white or yellow. The surface is smooth without projecting spicules. 

 The dermal membrane is thin, it is densely charged with chelse and sigmata; some small, circular 

 openings could be observed in it. 



The skeleton is highly irregular and confused in the first examined specimen, viz. that im- 

 bedding sponge-spicules, on account of the manner in which the sponge envelops the substratum. 

 The dermal skeleton is represented by dermal spicules which are found scattered through the whole 

 sponge; in single places they may form a bundle stretching towards the surface; in the dermal mem- 

 brane they are not seen, or at all events only some few, while, as said, the membrane is filled with 

 microscleres. In one place the dermal spicules were lying parallel and forming something like a 

 conical projection - - perhaps an oscular cone — but the state of the specimen did not allow this to be 

 decided. The main skeleton is still less developed, and the acanthostyli are only present in small numbers; 

 they are seen here and there with the head based on the substratum but otherwise quite confused and 

 pointing in all directions. While the skeleton is thus on the whole little developed, the sponge is on 



