94 BATHYDORUS LAEVIS SPINOSISSIMUS. 
BATHYDORUS F. E. Scuuuze. 
Thin-walled, sac-shaped, calyculate or lamellar Rossellidae (Rossellinae) 
with oxyhexasters and sometimes also hemioxyhexasters but no other micro- 
scleres in the choanosome. With hypodermal pentactines. The dermal 
spicules are usually chiefly tetractines (stauractines), but forms with fewer (one 
to three) or more numerous (five or six) rays may also occur, the forms with 
fewer rays sometimes predominating. The gastral spicules are hexactines, the 
distal ray of which may be differentiated so as to render these spicules somewhat 
pinule-like. 
Bathydorus laevis F. E. Scuuuze. 
F. E. Scuuuze, Abh. Akad. Berlin, 1895, 1896, p. 57, taf. 6, figs. 1-10. F. E. Scuunzn, Sitzungsb. Akad. 
Berlin, 1897, p. 535. I. Isrma, Annot. zool. Jap., 1898, 2, p.47. F. E. Scuuxzs, Indian Triaxonia, 
1902, p. 78, pl. 14, figs. 1-10. H.V. Witson, Mem. M. C. Z., 1904, 30, p. 51, pl. 5, figs. 11-13; pl. 
Gy figs. lp2: 
Bathydorus laevis spinosissimus, subsp. nov. 
Plate 14, figs. 1-32; Plate 15, figs. 1-22; Plate 16, figs. 1-24. 
All the specimens of this subspecies were trawled off northern Peru, Station 
4651, on 11 November, 1904; 5° 41.7’ S., 82° 59.7’ W.; depth 4063 m. (2222 f.); 
they grew on sticky, fine, gray sand; the bottom-temperature was 35.4°. Three 
specimens distinguished as A, B, and C were examined in detail. 
These sponges are related to Bathydorus laevis F. E. Schulze (loc. cit., 1896, 
p. 57). Within this species Wilson (loc. cit., p. 51) has distinguished the sub- 
species spinosus, which differs from the typical B. laevis by its spicules, particu- 
larly its dermals, which are much more spiny. In the specimens here described 
the dermals are still more spiny, and the pentactines, which are smooth in B. 
laevis spinosus, are also usually covered with spines. The name of this new sub- 
species refers to this further development of the spinulation. 
Shape and size. The best preserved specimens, one of which C (Plate 14, 
fig. 13), show calyces with rather broad bottom and a thin undulating wall. 
The margin, which is much torn, appears to have been lobose in the living sponge. 
In the calyculate specimens the two halves of the calyx-wall are quite flattened 
and pressed against each other. In the fresh state these calyxes were, no doubt, 
open. The other, fragmentary specimens are lamellae, which appear to have 
formed part of calyxes similar to those described above. The walls of the 
calyculate specimens are mostly 1-2 mm. thick, and thin out towards the margin. 
The fragmentary lamellae are 1-2.5 mm. thick. The largest calyculate speci- 
