EEPOET ON THE TETEACTINELLIDA. 
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Cydonium (f) geodinum (0. Schmidt). 
Stelletta geodina, O. Schiuidt, Spong. Algier., p. 20, pi. iv. fig. 5, 1868. 
Sjponge. — (?). Cortex thin. 
Spicules. — I. Megascleres. 1. Oxea, 2’755 by 0'022 mm. 2. Orthotrisene, 1*42 mm. 
long, cladi 0’34 mm. long. 
II. Microscleres. 3. Sterraster, spherical, 0’041 mm. in diameter (0. S.). 4. 
Choanosomal oxyaster, 0'056 mm. in diameter (0. S.). 5. Somal spheraster, 0‘015 
mm. in diameter (0. S.). 
Habitat. — Algiers. 
Remarks. — The measurements were obtained from a type-slide in the British Museum 
except those marked (0. S.), which are from Schmidt’s descriptions. The sponge 
evidently belongs to the Geodiidse, but may possibly have to be placed in a new genus. 
Genus Synops, Vosmaer. 
Section Pantceosa. 
Synops macandrewii (Bowerbank). 
Geodia macandrewii, Bowerbank, Proc. Zool. Soc. Lond., p. 196, pi. x., 1872. 
Sponge. — Massive, sessile ; surface even ; hispidated or hirsute with somal and 
cortical oxeas, dichotrisenes and protrisenes ; cortex, 3 ‘26 mm. in thickness, chiefly con- 
stituted of the sterrastral layer ; ectochrote and inner fibrous layer both very thin. 
Pores, from 0'05 to 0‘238 mm. in diameter, in sieves overlying incurrent chones, 0'636 
mm. in diameter ; oscules small, 0‘556 mm. in diameter, surrounded by a membranous 
margin, fringed with cortical oxeas, leading into small excurrent chones. 
Spicules. — I. Megascleres. 1. Somal oxea. 2. Cortical oxea, 0'35 mm. long. 3. 
Dichotrisene, rhabdome 7‘3 by OT 1 mm., protocladi 0’5 mm., deuterocladi 0'32 mm. long. 
Cladome depressed or cyathiform. 4. Protrisene, rhabdome fusiform, long, 0'0377 mm. 
in diameter; cladome subterminal, cladal centre situated 0T75 mm. from its oxeate 
distal termination, which sometimes bears a second cladome; cladi 0'1675 mm. long. 
5. Anatrisene, rhabdome 8‘92 mm. and over in length; cladi 0'18 mm., chord 0T675 
mm. long. 
II. Microscleres. 6. Sterraster, depressed, spherical, 0’27 mm. in diameter. 7. 
Somal spheraster, 0'0065 mm. in diameter. 8. Choanosomal spheraster, with a com- 
paratively large centrum and long conical actines, 0'025 mm. in diameter. 
(zool. CHALL. exp. — PARTLXIII. — 1887.) 
Err 34 
