SPONGES — WHITELEGGR. 455 



from three to six or more in a row. In the secondaries the 

 spicules are fewer and more closely arranged, and in the connect- 

 ing fibres the spicules occur sparingly, one or two to each, or they 

 may be absent. The terminal ends of the fibres pi-oject at the 

 surface, forming radiating tufts of spicules ; the intervening 

 spaces of the dermis also exhibit clusters of subradiate spicules. 



Megascleres : — sharp pointed oxea0"08 to 0-1 mm. by 0-0045 to 

 0-006 mm. Spicules from the British Museum fragment measure 

 from 0-08 to 0-09 mm. by 0003 to 0-004 mm. 



PACHYCHALINA, Schmidi. 



PACHYCHALINA RAMOSA, Lendenfeld. 



Chalinissa ramosa, Lendenfeld, Zool. Jahrb., ii., 1887, p. 772, 

 pi. XX., fig. 21. 



Stations 41, 44, 48, 50. 



This species is represented in the "Thetis" collection by sixteen 

 specimens ; they exhibit considerable variation in the diameter 

 of the branches and also as to the size and number of the 

 nodosities ; the whole of the branches in some examples are 

 strongly moniliform, in others they are subcylindrical with slight 

 constrictions at distant intervals. 



Sponge stipitate, much branched ; the branches are mostly 

 lateral, but frequently they are dichotomous, and often coalescent. 

 In contour they vary from cylindric to strongly undulate or 

 moniliform, and are from 5 to 15 mm. in diameter and from 200 

 to 400 mm. in length. 



Surface smooth, dense, and very finely porous ; internally the 

 texture is rather open, with a more or less square mesh. Oscula 

 numerous, pretty evenly distributed, slightly elevated, from 1 '5 

 to 3 mm. in diameter, on an average about 10 mm. apart, and 

 genei-ally situated on the rounded elevations. 



Primary fibres multispicular, about 0-05 mm. or more in 

 diameter and 05 mm. apart. Secondary fibres O'OS to 0-04, with 

 an axial core of six to eight or more spicules ; connecting fibres 

 slender, with four or more spicules in a row. The choanosome is 

 fairly sprinkled with spicules, and the dermal surface exhibits 

 numerous tufts of projecting oxea in clusters of about twelve or 

 more; the space between each bunch is about equal to the length 

 of the spicule. 



Megascleres : — sharp gradually pointed oxea 0*085 to 0-1 by 

 0-005 to 0-006 mm. 



There is a fragment from the British Museum which agrees in 

 appearance, texture, and spicular characters with P. ramosa, Ldf., 

 as above described. 



