320 
THE YOYAGE OF H.M.S. CHALLENGEK. 
face more or less even, outer surface growing out here and there into rounded tubercles. 
Pores and oscules inconspicuous ; the oscules are scattered over the inner surface, with 
circular slightly raised margins, from 0’16 to 0’2 mm, in diameter; the pores are 
restricted to the outer surface, situated singly in areas about 0‘14 to 0‘16 mm. in 
diameter, and surrounded by desinas ; these areas are mostly arranged in longitudinal 
series. 
Spicules. — I, Megascleres. 1. Desma (PI. XXXVL figs. 4-20), presenting the usual 
diversity of forms; approximately uniaxial varieties are about 0‘32 to 0‘35 mm. long, 
the protocladi of quadriradiate forms are about 0'16 mm. long ; in each case the diameter 
of the epirabd or cladus, exclusive of spines, is about 0’02 to 0‘025 mm. The epirabd or 
cladi are produced into short somewhat cylindrical processes, which usually bifurcate at 
the ends, each of the resulting smaller processes terminates in one, or usually more, 
simple or usually bifid spines with rounded ends. Beneath the epithelium of the ecto- 
some these spines are free, a,nd lie at about the same level, performing the function of a 
dermal spicule (PI. XXXVL fig. 29) ; deeper within the sponge they are interlocked 
and intergrown in the usual manner with the similar spines of adjacent desmas. On the 
free sides of the desmas that bound the larger canals the spines are stunted in their 
development, not growing out freely like those beneath the ectosomal epithelium. 
2. Oxea (PI. XXXVL figs. 2, 3), slender, cylindrical, sharply pointed, straight, curved 
or slightly sinuous, 0’75 by O'OOS mm,; where they occur as hispidating spicules they 
project about 0’5 mm. beyond the surface. 
Colour. — Ochreous-white, 
Habitat. — Off Amboina; depth, 15 to 25 fathoms. 
Station 33, off Bermuda, April 4, 1873; lat. 32° 21' 30" N., long. 64° 35' 55" W.; 
depth, 435 fathoms ; bottom, coral mud. Dredged. 
Station 56, off Bermuda, May 29, 1873; lat. 32° 8' 45" N., long. 64° 59' 35" W.; 
depth, 1075 fathoms; bottom, coral mud; bottom temperature, 38°’2 F. Dredged. 
Porto Praya, St. lago, Cape Verde Islands, August 1873 ; depth from 100 to 128 
fathoms. 
Bahia. 
Distribution. — Madeira, Portugal ; off Cape St. Vincent, “ Porcupine ” Expedition, 
374 fathoms (Carter). 
Remarks. — The foregoing description and that which follows are taken from the 
specimen dredged at Amboina, the only one obtained in a living state, all the others 
being dead and denuded skeletons merely. The comparison of all the specimens, and 
their identification with Azorica pfeifferse, will be discussed at the close of these 
remarks. 
The specimen from Amboina is a fragment embracing probably the larger part of the 
