479 
I 
they are especially dense in the axis of the sponge; from here 
arise indistinct fibres directed obliquely upwards and outwards. 
Both oxea and styli are taking part in the building up of the skeleton. 
Spicules. 1. Large styli (fig. 31a—b), only few in number; 
straight or a little curved, of even thickness over the greater part, 
then tapering to the sharp apex; length varying from about 450 
— 800 jii by a thickness of ca. 16—26 //; a few subtylostyli (fig. 
31b) are found. 2. Smaller styli (fig. 31c), very numerous, 
of the same shape as the foregoing, but only up to ca. 500 p in 
length, by 7—8 p in thickness. 3. Oxea (fig. 31 d), more or 
less curved in or near the middle, of even thickness over the 
greater part, then tapering to the sharp points; length varying from 
ca. 200—400 /t, by a thickness of 6—7 p. 
Hymeniacidon erecta nov. spec. 
(Fig. 32 a—b). 
Little Barrier Isl. 30 fathoms. Shell-bottom. 29/XIL1914. 
One specimen, attached to a shell ; cylindrical; ca. 45 mm long, 
3—4 mm thick. Surface even, but hispid; dermal-membrane thin, 
covering numerous subdermal cavities; several inconspicuous aper- 
tures, ca. 0,5 mm in diameter, are found, especially on the lower 
half of the sponge. Colour light grey; consistence tough, only a 
little elastic. 
The skeleton consists of a very dense feltwork of spicules, partly 
lying pell-mell, partly forming longitudinally directed fibres; these 
fibres cannot, however, be followed very far, as they soon dissolve, 
and other short fibres take up their tracts; the fibres are lying 
close together. 
Spicules. Styli (fig. 32 a), some nearly straight, some more or 
less, often irregularly, curved; in the axial portion of the sponge- 
body many styli are elongated so as to form irregularly curved, 
siender siliceum-threads. The styli vary in length from ca. 250 — 
650 p.hy a thickness of up to 8 p \ the threads may attain nearly 
the double length; they are not numerous. 
This sponge somewhat resembles Hymeniacidon haurakii in spi- 
culation, but is distinctly separated from that species in outer ap- 
pearance. 
