SILICIOUS AND HORNY SPONGES WILSON. 411 



Dendy. 1905 (p. 147), thinks the group is perhaps polyphyletic, 

 including sponges derived from several genera of Gelliinae and 

 Renierinae through strong development of spongin accompanied 

 in some cases by loss of microscleres. 



Genus PACHYCHALINA O. Schmidt (1868). 



PachychaUna O. Schmidt, 186S, p. S. — Ridley and Dendy, 1SS7, p. 19. 

 Not tubular. Surface smooth or spinose. Skeleton composed of 

 stout fibers containing numerous spicules arranged in several rows. 



PACHYCHALINA FIBROSA Ridley and Dendy. 



Pachychalina fibrosa Ridley and Dendy, 1887, p. 19. 



Station D5136, two specimens possibly representing pieces of an 

 elongated sponge which had broken off from the general body and 

 had healed, for the surface is everywhere covered with dermal mem- 

 brane and spines. Station D5141, an elongated branching speci- 

 men. These specimens are well represented by the two figures of 

 the species given by Ridley and Dendy (1887, p. 21, pi. 4, figs. 3, 4) 

 and even in size are close to the sponges there portrayed. The gen- 

 eral shape of the body, size and spacing of the spines, large size 

 of the oscular depressions showing on the bottom the mouths of the 

 efferent canals, appearance of the skeletal reticulum through the 

 dermal membrane, all constitute points of resemblance between the 

 Challenger and Albatross sponges. 



The fibers of the main skeleton are 70-175 \l thick, with slenderer 

 ones, and are completely filled with spicules. Abundant spicules 

 are scattered between the fibers. 



In the dermal reticulum, the fibers are 8-22 \k thick, some uni- 

 spicular, more polyspicular (2-3—1 rows), with abundant spongin; 

 meshes rounded and about as wide as the length of a spicule or less. 

 This is evidently the finer reticulation described by Ridley and 

 Dendy. Below and distinct from it are the superficial tangential 

 fibers of the main skeleton. Such is, I take it, the typical arrange- 

 ment, although quite often the coarser fibers do not lie beneath 

 but form an actual part of the dermal reticulum. They evidently 

 constitute the " coarser reticulation " of Ridley and Dendy. 



The spicules are oxeas of the more cylindrical type, ends some- 

 times rounded; 88-96 by 3-4 \i. 



Ridley and Dendy's types were from the Atlantic, off Bahia and 

 Bermuda; a specimen from the Philippines was referred by them 

 (1887, p. 22) to an unnamed variety of the species. Lindgren, 1898 

 (p. 293), identified as this species specimens from Java and Cochin 

 China, and by merging certain species added to the distribution 



