SILICIOUS AND HORNY SPONGES WILSON. 377 



3. Anatriaene. Absent in the radial bundles of the general body, 

 common in the root bundles of the lower body and- base. Spicules 

 characterized by a very flat cladome. In a typical spicule (pi. 48, 

 fig. 4, a) rhabdome is several millimeters long, 12 [x thick above; 

 clads short, stout, almost at right angles to the rhabdome, about 

 24 [x long, 12 [x thick at the base. Slenderer but similar spicules also 

 occur, down to those with rhabdome 5-6 \l thick and clads 8-12 yi long. 



The anatriaenes show a considerable tendency to vary. Thus 

 spicules with three short rounded clads, which may be only 4 \i 

 long, occur (pi. 48, fig. 4, b). Monaenes, larger than the common 

 anatriaenes, occur; rhabdome 16 [x thick, clad 20 pu long and 

 16 [A thick (fig. 4, c). All the clads may be so degenerate that the 

 spicule is virtually tylote at this end (fig. 4, d) . Rarely the rhabdome 

 is prolonged beyond the degenerate clads (fig. 4, e). 



4. Sigmas. Abundant in the dermal membrane of the poriferous 

 pits and between them, and in the cloacal wall; also abundant 

 throughout the interior of the sponge, 12-16 y. long, of the usual 

 shape. 



Holotype.— Cut. No. 21314, U.S.N.M. 



The species is close to Tetilla (Cinachyra) mertoni, Hentschel 

 (1912, p. 332), from the Kei Islands, a form with larger pits that 

 reach a diameter of 3 cm. In T. mertoni there are several cloacae, 

 apparently very similar to the pits; the anatriaenes, while they have 

 a flat cladome, are of a slender type and the spicules are apparently 

 not confined to the root bundles. The protriaenes are slenderer, with 

 larger clads, than in T. patctifera; they are also said to be less abun- 

 dant than the anatriaenes. The sigmas in Hentschel's species have 

 truncated or slightly dilated ends. The Philippine species also re- 

 sembles, especially in external appearance, Tetilla {Cinachyra) vac- 

 cinata from the Indian Ocean, Dendy 19215 (p. 14). There are 

 however skeletal differences and also differences concerning the 

 oscula. 



Genus CRANIELLA O. Schmidt (1870). 



Craniella O. Schmidt, 1870, p. 66.— Soixas, 1888, p. 30. — Topsent, 1920&, p. 7. 

 Tcthya Lendenfeld, 1903, p. 23. — Lamarck part, Lendenfeld, 1906, p. 69. 



The ectosome is differentiated into an inner fibrous layer, traversed 

 more or less radially by cortical oxeas, and an outer collenchymatous 

 layer excavated by subdermal cavities. Pores scattered over surface 

 of sponge. Oscula distinguishable from pores and usually few in 

 number. The microscleres have been lost in some species. 



As to the propriety of the name Craniella, instead of Tethya, see 

 Donatio,. Lendenfeld, 1906, merges Tetilla (plus Chrotella) and 

 Craniella ( Tethya) because of the existence of forms intermediate in 



