SPONGES 



EoPLECTELLiXAE, F.E.S. Tubular forms with transverse terminal sieve- 

 jjlate ; the body wall perforated by circular parietal gaps ; distal ray of 

 dermal oxyhexactine bearing a Horicome. Genera — Euplectdla, Owen 

 (Fig. 15) \ liegadrella, O.S. (Fig. 18). {b) Sub-Family 2. Holascixae, 

 F.E.S. Tubular, without parietal gaps or superficially situated floricomes ; 

 with parenchymal oxyhexasters. Genera — Holascm, F.E.S. ; Malacosaccus, 

 F.E.S. (c) Scb-Family 3. Taegerixae, F.E.S. Sack-like or tubular, 

 the thin body wall perforated by parietal gaps of irregular size and 

 distribution. The skeletal lattice work of the body wall forms an 

 irregular meshwork ; with superficially situated floricomes. Taegeria, 

 F.E.S. ; WaUeria, F.E.S. Genera incerti sedis — Hahrodidytm, W. Th. ; 

 Eudictijum, ^Marshall ; Dictyocabjx, F.E.S. ; Rhabdodidytiin, O.S. ; Rhabdo- 

 pledelht, O.S. ; Hyalostylus, F.E.S. Family 2. Hertwigidae, Tops. 

 (1892). Skeletal framework composed of hexactines and diactines united 

 by synapticulae ; the free parenchymal spicules are hexactines of two 

 kinds, one confined to the surface ; characteristic hexaster, one with four 

 sickle-shaped hooks on each of the principal rays. Genera — Hertuigia, 

 O.S. ; Tradiycaulus, F.E.S. Family 3. IAscoxematidae, Gray (Schulze, 

 1897). Dermal and gastral skeleton containing pinuli with spined radial 

 rays projecting freely ; hypodermalia pentactinal, but no hypogastral 

 pentactines ; parenchymal discohexasters. Genera — Asconema, Sav. 

 Kent. (Fig. 17) ; Axdasciis, F.E.S. ; Sympagella, O.S. ; Saccocalyx, F.E.S. ; 

 jCaulo})hacu^, F.E.S. [Eoc], (Fig. 20, C). Calycosoma, F.E.S. ; Calycosaccus, 

 F.E.S. Family 4. IRossellidae, F.E.S. (lijima, 1898). The dermalia 

 always without distal radial rays. («) Sub-Family 1. Leucopsacixae, 

 lijima. Dermalia not diflferentiated into autodermalia and hypodermalia. 

 Genera — Leucopsacns, lij. ; ChaiDiojileclella, lij. ; Flacopleyma, F.E.S. ; 

 Aulocaly.r,Y.E.ii.; E urypley ma, F.E.H. (Fig. 20, A) ; Catdocalyx, F.E.S. (b) 

 Sub-Family 2. Laxuginellixae, F.E.S. "With distinct auto- and hypo- 

 dermalia ; without octastcrs ; plumicomes present ; with or without 

 oxyhexasters. Genera — Lanuginella, O.S. ; Lophocalyx, F.E.S. ( = Poly- 

 lophius, F.E.S.) ; Mellonympha, F.E.S. (c) Sub-Family 3. IIIossellixae, 

 F.E.S. With distinct auto- and hypo-dermalia ; without octasters or 

 plumicomes ; oxyhexasters always present. Genera — Bathydorus, F.E.S.; 

 l^itrollula,l\]. ; jCrateromorpJui, Gray [Eoc.]; Atdocho7i£,F.E.S. ; Hyalascus. 

 lij. ; Rossella, Crtr. (Fig. IG) ; Apliorme, F.E.S. ; Aulosaccus, lij. (d) Sub- 

 Family^ |t Acanthascinae, F.E.S. With distinct auto- and hypo- 

 dermalia ; octasters and oxyhexasters always present. Genera — Stauro- 

 cali/pfus, lij. ; Rkabdocalyptm, lij. ; Acanthascus, F.E.S. ; Acanthosacciis, 

 F.E.S. 



[Rossellidae as yet undescribed ; SchawUnnut, Trichasterina, and 

 Sajphidiujn, Schulze, 1899.] 



Order 2. Amphidiscophora, F.E.S. 



Amphidiscs always present in the limiting membranes. No hexasters 

 in tlie parenchyma. Always witli an anchoring root tuft. Ciliated 

 chambers irregular in shape, and not sharply marked off from one 

 another. 



t Fossil and receut. 



