VEG A-EXPEDITIONENS VETENSKAPLIGA ARBETEN. 437 
The large and long acerate spicules (Plate 24, fig. 22) are very 
numerous, forming the greater part of the radiating fasciculi. 
The length is 3,,—5 mm. They have the greatest diameter at 
the middle, tapering towards the fine and long points. They 
are usually straight, sometimes, however, slightly curved towards 
the terminations. 
The small acerate spicules (Plate 24, fig. 23). These spicules 
are less numerous than the large ones and more variable in 
size. Most of these spicules are 0,8 mm in length. 
The porrecto-ternate spicules (Plate 24, fig. 24, 25). These spi- 
cules are very slender, generally curved towards the points. 
One of the three branches is usually longer than the other two. 
The length of the shaft of this spicule is about 0,3 mm, the 
short branches 0,07 mm and the long one about 0,14 mm in 
length. The branches are generally straight. 
The recurvo-ternate spicules (Plate 24, fig. 26) are slightly 
thicker than the porrecto-ternate; they are also slightly curved. 
flnckElen sta FOfTthershartiISstöR mm; tie pramnehes are of vie 
same size, Viz. 0,14—0,2 mm. Both these last-mentioned spicules 
occur in about the same quantity. 
The sigmoid bihamate spicules (Plate 24, fig. 27, 28) are very 
numerous; their length is about 0,03 mm. 
This species has a certain resemblance to Tetilla polyura 
O. S.7), as in the porrecto-ternate spicules, in the knotty sur- 
face, and in the ovoid form. But our new species of Tethya 
has not sigmoid-bihamate spicules of the same kind as T. po- 
lyura Ö. S. In the last-mentioned species these spicules are 
knotty, but they are smooth in Tethya sibirica Fristedt. "The 
roots are not of the same structure. Besides, the surface of T-. 
polyura Ö. S. is more hispid than that of Tethya sibirica Fristedt. 
Colour. "The colour of specimens preserved in spirit is 
yellowish or yellowish grey. 
Habitat. Uhatanga Bay, Lat. 75”, Long. 113? 50' E., depth 
15 fathoms (41 V.); Actinia Bay, depth 5—10 fathoms (29 V-.); 
Pitlekai (1006 V.). 
"y O. Sch midt, Grundzäge einer Spongienfauna des Atlantischen Ge- 
bietes, 1870, pag. 66, Taf. 6, Fig. 8. 
