SILICIOUS AND HORNY SPONGES WILSON. 439 



160-180 [x, smaller ones down to a length of 100 ^ occurring sparsely. 

 The very small diancistra of the type could not be found. The 

 sigmas are only 16-18 \l long. The diancistra and sigmas occur 

 abundantly in the dermal membrane and in the interior. No rosettes 

 were observed, the diancistra apparently always occurring singly. 

 Holotype.— Cat. No. 21269, U.S.N.M. 



Subfamily Ectyoninae 



Ectyoninae Ridley and Dendy, 1887, p. 128. — Tobsent, 1894c, p. 11. — 

 Lundbeck, 1905, pp. 1-2. 



Desmacidonidae in which the spiculo-fibers of the skeleton are 

 echinated by monactinal, usually spined, spicules. In incrusting 

 forms the corresponding spicules project vertically from the basal 

 skeletal plate. 



Genus CLATHRIA O. Schmidt (1862). 



Clathria Schmidt, 1862, p. 57.— Dendy, 1S95, p. 31.— Hentschel, 1911, 



p. 368. 

 Clathria Schmidt plus Rhaphidophlus Ehlers, Ridley and Dendy, 1887, 



pp. 146, 151. 

 Clathria Schmidt plus Rhaphidophlus Ehlers, Topsent, 1894c, pp. 14, 15. 



Generally erect sponges. Main skeleton a reticulation of spiculo- 

 fiber usually with much spongin; the fibers include skeletal styles or 

 subtylostyles, generally smooth but in some species more or less 

 spinose, especially at the basal end ; fibers echinated by spined styli 

 (acanthostyles). In the ectosome and elsewhere there are usually 

 free stylote megascleres, often slenderer and shorter than the skeletal 

 styles; these may form a radial dermal crust {Rhaphidophlus). 

 Microscleres, small palmate isochelas and toxas (or rhaphides), to- 

 gether or separately ; microscleres sometimes absent. 



Hentschel, 1911, and Hallman, 1912 (p. 205), would include forms 

 in which the echinating spicules are smooth. The toxa, as is known 

 (see Wilson, 1902, p. 398), may vary in the same specimen from the 

 typical shape to that of the rhaphid, both toxas and rhaphides some- 

 times forming loose bundles. Hentschel has recently (1912, p. 359) 

 drawn attention to this fact. 



CLATHRIA FRONDIFERA (Bowerbank), var. SETO-TUBULOSA. new variety. 



Halichondria frondifera Bowerbank, 1875, p. 288. 



Clathria frondifera Ridley, 1884, pp. 448, 612. — Ridley and Dendy, 1887, 

 p. 149. 



Station D5136, one specimen. Station D5141, several fragments 

 and two larger specimens. 



Primarily in this sponge there are irregularly lamellate branches, 

 bearing ridges and terminating above in free processes which project 



