465 
! 
Microcionia hetevospiculata nov. spec. 
(Fig. 20 a—m.) 
I Colville channel. 35 fathoms. Sand, mud. 21/XII,1914. 
One specimen enerusting on a shell, as a 0,3 mm thin layer. 
The skeleton consists of spicula-tufts, raising perpendicularly 
, from the body of attachment (fig. 20 a); they are built of acantho- 
styli, the bases of which are imbedded in short stout spongin- 
: columns: the tufts are standing so close to one another, that the 
J spicules often overlap one another from neighbouring columns; the 
j subtylostyli are for a great deal scattered irregularly throughout 
I the body, but in many places they are arranged as small brushes 
I together with and partly continuing the acanthostyli-tufts. Both 
^ forms of microscleres are scattered abundantly in the choanosome. 
\ Spicules. a. Megascleres. 1. Acanthostyli (fig. 20b—c), the 
i base often subtylostylote; the bigger ones only spined at the base, 
D the small ones spined all over; they are slightly curved, tapering 
evenly to the sharp points; length varying from ca. 80 — 400 /.t, 
^ a common length is 300 /i; thickness up to ca. 14 //. 2. Sub- 
i ty losty li (fig. 20 d), or styli, with rounded base, tapering evenly 
ft 
towards the sharp points; straight or only a little curved; length up 
to 320 X 4 ^ in thickness. b. Microscleres. 1. Isochelae (fig. 
I 20 e—f), of the usual type, only a little curved, length 10—15 //. 
I 2. Abnormal Isochelae (fig. 20g—m), these bodies are of a 
[ very strange shape; they somewhat resemble the curious micro- 
I scleres figured by Den dy (6) on plate 14, fig. 4. Accordingly I 
have tried them with water after the method of Dendy 1916 (4), 
but they do not seem to be of the same nature as the colloscleres; 
they seem to have developed from isochelae without fimbriae or 
I broad teeth, or even beginnings thereto. I have seen such imper- 
feet chelae, whose teeth have not yet coalesced; and there are 
others the teeth of which have coalesced, so as to form oval rings; 
the foramen, which is being built in this way, is then filled up 
more or less with siliceous matter forming a more or less conti- 
I nuous lamella. Length 12—18 p. These curious bodies also re- 
^ semble the clavidiscs of Merlia, thus perhaps giving a due to the 
origin of these spicules. At any rate the occurrence of degenerated 
chelae, as I think they are, in the genus Microcionia is extremely 
1 interesting. 
I Vidensk. Medd. fra Dansk naturh. Foren. Bd. 77. 30 
t 
