13 
on the top of the body. The body of the largest specimen mea- 
sured 1.5 c.m. in diameter. Gigantic stellates, and M.ta. ® > 90°, 
_ rather frequent. 
2. Thenea muricata var. 8. having a more hispid surface, a 
darker greyish colour, straight roots, no bundle of long spieules 
on the top of the body. The body of the largest specimen mea- 
sured 6 c.m. in diameter. Gigantie stellates and M. ta. & > 90°, 
when present, very rare. 
3. Thenea muricata var. y. having a very hispid surface, a dark 
‚green-greyish colour, wrinkled ramifying roots, no bundle of long 
spieules on the top of the body. The body of the largest speci- 
men measured 2 c.m. in diameter. Gigantic stellates but no M, ta. 
®> 90°. 
 Schmidt’s Tisiphonia fenestrata appears to me to belong to the first 
variety, Bowerbank’s Tethea muricata to the second. In the Arctic 
Ocean the latter (var. $.) seems to be the most common variation. 
All authors, Schmidt, Bowerbank, Wyville Thomson a. o. who 
give illustrations of our Sponge, seem to have had very mutilated 
specimens. Thomson’s Tisiphonia agariciformis is, I believe, only 
a partly macerated specimen, perhaps of a fourth variety. 
6. Isops sphaeroides n. sp. [Pl. I. Figg. 10 and 11; pl. II. 
Figg. 27, 28, 39—49; pl. IV, fig. 116.] 
Diagn.: Corpus globulosum. Spieula indicantia: ac? (f) | tr. ac | M. 
ta. = 90° | M. ta.d < 90° | M. ta. d. bif. | gl. | st | glet. | 
Local: Lat. 71°12’5N.; long. 20° 30'5 E. [neighborhood of Ham- 
merfest]. (July 2, 1879). 
Depth. 135 Fathoms. 
Special description. 
a. External character. 
There are of the second Dutch Barents-Expedition two specimens 
dredged up by Mr. van Lith de Jeude. Both are globular. The 
greater spceimen (Pl. I Fig. 10) is hispid by the protruding spi- 
eula; the other one doesn’t show any protruding spiculation. In the 
