B. Special. 2. Demospongiae. 9 



by a narrow ectochone, short endochone, and subcortical crypt. Either the 

 ramifying [ultimate] incurrent canals start from the crypt directly, or there start 

 from here a few [intermediate] canals which unite again in [inner] lacunae, from 

 which arise the ultimate incurrent canals. The hemispherical flagellate chambers 

 are diplodal, the excurrent canals lead into crypts, endochones, and ectochones 

 surmounted by a dermis and a group of proctions; these lie in depressions, 

 generally shallow, sometimes deep enough to form an osculum, 100 or 200 chones 

 in each depression. - - /. maculosus. Procts and stomions scattered without order, 

 chambers diplodal. - - Synops anceps n. Stomas, narrow chones (ectochone long), 

 large subcortical crypts, narrow intermediate canals, wide inner lacunae, small 

 diplodal chambers, wide excurrent chones. Groups of procts are in depressions 

 on conical prominences, stomas scattered. - - Caminus vulcani. Stomions, sub- 

 dermal cavities, chones with insignificant endochones, subcortical crypts, inter- 

 mediate canals and inner lacunae; generally but one proct. Erylus euastrum. 

 Each stoma is the opening of a sphiucterless chone, from the rudimentary crypts 

 start the ultimate incurrent canals, flagellate chambers diplodal and ellipsoid: 

 stomas scattered ; one or more procts each on a conical process. -- Penares hellcri. 

 Generally one wide proct; chambers diplodal, afferent system as in E. euastrum. 

 Stryphnus mucronatus (including S. carlonanus). Stomas open into wide com- 

 municating lacunae : under the cortex arc small crypts, narrow intermediate 

 canals, and wide inner lacunae; generally one proct. Ancorina cerebrum. 

 Stomions (scattered) and short lacunae open into irregular chones followed by 

 crypts and the ultimate incurrent canals ; chambers diplodal ; excurrent chones 

 also irregular. -- Stcllelta grubei. Stomions and sometimes long canals, sometimes 

 subdermal cavities, debouch into indistinct chones; there are crypts and large 

 inner lacunae; chambers ellipsoidal and diplodal. Poecillastra fragilis. A 

 laminar sponge with stomas on the convex, procts on the concave side. Sub- 

 dermal cavities open into wide lacunae from which start the ultimate incurrent 

 canals. - - P. cumana. Thin and leaf-like sponge, stomas and procts on opposite 

 sides, whole canal-system lacunar. 



Lendenfeld( 6 ) ejects Placospongidae from the Tetractinellida, placing them near 

 the Suberitidae [cf. infra]. Canal-system. Ancorina radix. Fine canals lead 

 from groups of external pores into a vertical afferent canal -stem with a con- 

 striction comparable to a chonal sphincter , this leads to a cavity called sub- 

 dermal , comiminicating with a tangential layer of canals. In A. cerebrum 

 the afferent canals appear to branch directly from the Subderrualraurn : the 

 efferent chones are larger, grouped together, and often enclosed in Praoscular- 

 raume. A. mucronata differs mainly in a branching afferent canal arising directly 

 from the chone without intermediate cavities ; Sollas's account is erroneous. 

 Ecionemia (Penares of Vosm.) hetteri has pores opening into an irregular subdermal 

 plexus of canals. Erylus discophorus. Each pore has a short chone-like canal 

 leading into irregular subdermal spaces from which small branches unite into 

 wider centripetal canals. These show numerous annular membranes, still more 

 marked in the efferent system. In E. mammillaris rarely more than one pore-canal 

 opens into the same subdermal space. -- Geodia conchilega. Afferent pores mostly 

 on exposed convex parts, efferent in hollows where the rind is thin. Many fine 

 pore-canals, with walls too delicate to be made out, except in tangential sections, 

 lead to each afferent chone; from this wide afferent canals branch into smaller 

 ones which lead to the diplodal spherical flagellate chambers. Efferent canals are 

 transversely corrugated and have ring-membranes ; each has a chonal sphincter, 

 longer and nearer the surface than in the afferent system, and communicating by 

 several fine canals with the exterior. G. cydonium has one large praeoscular 



