REPORT ON THE TETRACTINELLIDA, 
257 
current cliones similar, both provided with sieve-pores scattered over both inner and 
outer surfaces but absent from the margin of the cup. Cortex 0'8 mm, in thickness, com- 
posed almost entirely of the sterrastral layer. 
Spicules. — I. Megascleres, 1. Somal oxea, fusiform, usually curved, sometimes 
irregularly, 27 by 0'032 mm. 2. Cortical oxea, small, fusiform. 3. Orthotrisene, rhab- 
dome conical, 2'4 to 2'6 by 0'078 mm., cladi from 0’23 to 0’38 mm. long. 4. Anatrisene, 
rhabdome cylindrical, long, 0'018 mm. in diameter, cladi O'l mm., chord 0'0839 mm., 
sagitta O'll mm. long. This spicule is more than usually abundant. 
II. Microscleres. 5. Sterraster, spherical or ellipsoidal, depressed, 0'0775 mm. in 
diameter, or 0’09 by 0'0775 by 0‘058 mm. 6. Somal spheraster, minute, centrum forming 
the greater part of the spicule, the actines occurring as short irregular prominences, 
diameter 0‘005 mm. 7. Subcortical spheraster, centrum large, actines conical, sharply 
pointed, numerous, diameter 0’02 mm, 8. Choanosomal oxyaster, centrum small or 
absent, actines not numerous, conical, smooth, 0’032 mm. in diameter. 
Colour. — Cream-white. Size, 250 mm. by 334 mm. across the mouth of the cup. 
Habita t. — J apan. 
Remarks. — In general form this sponge much resembles Synops neptuni (p. 227), 
from which it is distinguished not only by the character of the oscules, but by the 
greater variety and larger size of its spicules. The sponges which it most nearly 
approaches in the characters of its spicules are Geodia nodastrella. Carter, and Geodia 
carteri ; its general form distinguishes it from both, and from the latter it is also distin- 
guished by the absence of a well-developed ectochrote. 
Cydonium pleiades, n. sp. 
Sponge . — (?). 
Spicules. — I. Megascleres. 1 . Somal oxea, fusiform, 3’4 by 0’06 mm. 2. Cortical 
oxea, about 0'25 by 0'0064 mm. 3. Dichotrisene, rhabdome 3'34 by 0'078 mm., cladi 
bent backwards at the point of first dichotomisation, subsequently dichotomising once, 
twice, or three times ; in a thrice dichotomising example the protocladi measured 0*258 
mm., deuterocladi 0*045 mm., tritocladi 0*026 mm. in length; in one dichotomising four 
times the protocladi measured 0*27 mm., deuterocladi 0*064 mm., tritocladi 0*064 mm., 
tetartociadi 0*0387 mm, in length. 4. Anatrisene, rhabdome 0*032 mm, in diameter, 
cladi 0*148 mm., chord 0*161 mm,, sagitta 0*142 mm, in length. 
II. Microscleres. 5. Sterraster, spherical, depressed, 0*09 by 0*071 mm. 6. Somal 
spheraster, minute, centrum comparatively large, actines short, cylindrical, truncate, 
0*006 mm. in diameter. 7. Subcortical spheraster, centrum large, actines conical, almost 
sharply pointed but rounded off at the ends, 0*016 mm, in diameter. 8. Choanosomcd 
(ZOOL. CHALL. EXP. — PART LXIII. — 1887.) Err 33 
