SILICIOUS AND HORNY SPONGES WILSON. 413 



of these thick fibers do lie strictly in the dermal skeleton, the fine 

 dermal reticulum on both sides of such a fiber not extending over it 

 but meeting and uniting with it. 



The spicules are strongyles, very slightly curved, 70-80 by 3-4 \i, 



Holotype.— Cat. No. 21276, U.S.N. M. 



This variety is well represented by Hentschel's figure (1912, pi. 15, 

 fig. 7) of Pachychalina diffusa (Ridley), var. afilnis from the Aru 

 Islands, but the main fibers in Hentschel's sponge are poor in spongin 

 and the spicules (tornotes) measure 80-112 by 5-7 \).. In the type of 

 this species, P. diffusa, the fibers have more spongin, but the spicules 

 are about as thick as in Hentschel's variety. (See Ridley and Dendy 

 1887, p. 22.) In ranging the Albatross sponge under P. fibrosa rather 

 than P. diffusa. I have laid the greater weight on the size of the 

 spicules and the less on the amount of spongin in the fiber. 



Genus SIPHONOCHALINA O. Schmidt (1868). 



Siphonochalina O. Schmidt, 1868, p. 7. — Ridley and Dendy, 1887, p. 29. 



Tubular Chalininae in which the outer surface of the tube is smooth 

 or comparatively so — that is, without the spinous processes of 

 Spinosella. 



SIPHONOCHALINA FASCIGERA Hentschel. 



Plate 42, fig. 2. 

 Siphonochalina fascigera Hentschel, 1921, p. 398. 



Three dried specimens, one not labeled, the others from Tomahu 

 Island (south of Boeroe or Bouro Island) ; large pieces of seven 

 tubes, in alcohol, from Tomahu Island ; two alcoholic specimens from 

 Station D5136. 



The finest specimen, dried, from Tomahu, consists of about 10 

 tubes arising from a common base. The tubes are larger and with 

 thicker walls than in Hentschel's specimens (from the Kei Islands). 

 The height of the tubes is 300-360 mm., diameter about 25 mm., wall 

 about 3 mm. thick, thinning away to an edge round the large ter- 

 minal aperture. Surface varies from smooth to conulose, the upper 

 part of the tube smoother than the lower. The other dried specimens 

 ■consist, each, of a few tubes united below ; in these the outer surface 

 is smooth. 



The Tomahu Island alcoholic specimens, diameter of which 

 reaches 30 mm., wall 2-3 mm. thick, show one case of branching, 

 several cases of ordinary lateral fusion between tubes, and some inter- 

 esting tendril-like structures. These are solid slender outgrowths, 

 1-2 mm. thick, reaching 30 mm. in length, which on two tubes have 

 developed in large number especially round the cloacal edge but 

 also from the neighboring lateral wall. Most of them taper from 



