434 FRISTEDT; SPONGES. 
Polymastia penicillus Mont. (Vosmer). 
Polymastia penicillus, Vosmer, Niederländ. Archiv för Zoolog., Supplementb. 
T, po26 PIE pre 22TSAROret AN fos Ke 
Numerous specimens represent this species. All the spe- 
cimens are furnished with well developed mammulze, which 
often are inflated at the free terminations. This species is 
very variable in outer shape, but the spicules are similar in 
all forms. I have labelled numerous species from the coast 
of Sweden as Polymastia mamillaris O. F. Möller (Bow.), be- 
cause they agree well with Bowerbank”'s description of the 
species, so named. But the specimens from the arctic regions 
agree more with forms described and figured by Vosmer as 
P. pemicillus Mont. (Vosmer), and therefore I have labelled 
these as Polymastia pemicillus Mont. (Vosmer), the only diffe- 
rence between these two forms existing in their outer shape, their 
spicules being of the same size and kind. The forms labelled 
as Polymastia pemnicillus Mont. (Vosmer) are also generally 
hirsute at the margins and on the upper surface; the other 
forms are more smooth. The mammule are exceedingly vari- 
able in size and number. 
The sponge is usually attached to stones, shells and other 
hard objects. 
The colour varies from yellow to yellowish grev or light 
ash-grey. The largest specimen is 60 mm in length, 40 mm 
in breadth, the thickness not exceeding 15 mm. The single 
smooth specimen in the collection of aretic sponges has 
numerous straight, slightly compressed mammule, the length 
being about 5 mm. 
Habitat. "The east-coast of Greenland, depth 130 fathoms 
(580: 5.); -North-East from .Petrovski Bay, Lat. T6” 520tEonet 
116? E.; depth 36 fathoms (39 V.); Lat. 76” 401, Tong llörvsoree 
depth 35 fathoms (40 V.); Matotschkin schar, Gubin Bay, depth 
5—15 fathoms (42 N. S:); Spitzbergen, Lat. 80? 7', Long 16:540HH 
depth 60 fathoms (256 Sp-.). 
Polymastia paupera n. sp. 
Plate 24, fig. 21. 
During the expedition to Greenland in the year 1883 
only one specimen was dredged up. This specimen, broken 
