REPORT ON THE TETRACTINELLTDA. 
807 
Corcdlistes tliomasi, n. sp. (PI. XXXY. figs. 12, 13 ; PI. XV. figs. 40-46). 
Sponge (PI. XXXV. figs. 12, 13). — A small, somewhat ear-shaped plate, margin 
rounded, erect, attached by an incrusting base. Oscules numerous, small, with raised 
margins, scattered at nearly equal distances apart over the convex face of the plate 
(PL XXXV. fig. 13). Pores scattered evenly on the concave side of the plate (PL XXXV. 
fig. 12), each porous area singly perforated by a central circular pore. 
Spicules. — I. Megascleres. 1. Desma, epirabd stout, cylindrical, cladi similar, rather 
short, bearing somewhat stud-shaped tubercles, presenting a short, cylindrical stalk or 
neck, which terminates in an expanded, somewhat hemispherical head, about 0'032 to 
0’064 mm. in diameter, bearing low, rounded, secondary tubercles, arranged in groups, 
those on the sides being frequently elongated longitudinally. The ends of the cladi 
terminate in expanded lobate processes, wdiich grow over the sides of neighbouring desmas, 
closely embracing the necks of the tubercles. The breadth of the cladi is usually about 
0‘045 to 0'052 mm., their length 0'065 to 0’097 mm. 
2. Dichotriaene (PL XV. figs. 40-42), rhabdome stout, short, conical, strongylate ; 
protocladi relatively very short, deuterocladi long ; both spreading horizontally, bearing 
on their distal face short, rounded, conical tubercles which project forwards, growing 
out into tubercles at the edges also. Ehabdome 0‘366 by 0‘039 mm., often 0'013 mm. 
wide at the end where rounded off, protocladus 0'0194 by 0'032 mm., deuterocladus 
0'084 by 0'026 mm. 
II. Microscleres. 3. Strongylospire (PL XV. fig. 43), undulating or vermiculate rods, 
axis straight, curved, or irregularly bent, 0‘026 to 0'032 by 0'004 mm. 
4. Spiraster (PL XV. figs. 44-46), of various forms, approaching the metaster and 
amphiaster types, 0 ’032 mm. long, a single spine from 0'008 to 0’016 mm. long. 
5. OrthotricJiites ; scattered amongst the spicules obtained by boiling out with nitric 
acid on the glass slide, are fine siliceous filaments distinctly double-contoured, but too 
fine to afibrd measurements of thickness, sharply pointed at each end, and about 0T6 mm. 
long. 
Colour. — In the dried state yellowish-white. 
Habitat. — Station 192, off the Ki Islands, south of Papua, September 26, 1874; 
lat. 5° 49' 15" S., long. 132° 14' 15" E. ; depth, 140 fathoms ; bottom, blue mud. 
Remarks. — This specimen so closely resembles in form and size another belonging 
to a different genus and species, Azorica marginata, obtained at the same station, that 
they were originally mistaken for one another, and the whole sponge of Corallistes 
thomasi was figured along with the desmas of Azorica marginata. 
The present sponge is about 16 mm. wide, 11 mm. high, and 4 mm. thick. The 
oscules occur as central perforations about 0‘048 mm., at the bottom of circular craters. 
