TETHY0EEHAPHI8. 53 



(C) Small spicules, with slender cylindrical rays without terminal thickenings, 

 0-02-0-03 millim. in diameter, scattered throughout the interior, more numerous 

 than the foregoing, but also rather scarce. — (3) Strongijlote Microsdera. These 

 form a dense layer 0-08 millim. in thickness below the outer surface, and 

 extend down the walls of the inhalant canals ; they are also found in abun- 

 dance scattered throughout the interior of the s])onge. These spicules are mostly 

 straight and rounded at each end ; strongyla ; they have a slightly roughened 

 surface, and measure 0-012 x 0001 millim. Some of these spicules are 

 slightly bent, whilst others are angularly bent; the angle varies from 180- 

 120 degrees ; such forms may produce a third ray which appears sagittal, 

 and a number of transition forms between the diacts and triacts have been 

 observed by me, similar to those described by F. E. Schulze in Plal'ina. 

 But there are also some transition forms between these triacts and polyact 

 stellates. The whole series represents the development of these diacts from 

 the slender-rayed stellates by a reduction of the ntimber of rays. 



Geogeapuical Disteibution. — East coast of Australia: Port Jackson, 

 N. S. W. {Ramsay). 



Tethyorrhaphis tuberculata, n. sp. 



Spherical or subspherical sponges, \Ahich are attached by a broad base, 

 equal to about two thirds of the diameter. Broader than high : 25 x 35 to 

 30x40 millim. Surface tubercular. Tubercles of uniform width, hut not of 

 uniform height throughout ; rounded, conic, or mammilliform, di\ided by a 

 reticulation of sharp incisions ; 2*5 millim. wide at the base, and from 1 

 to 3 millim. high. Oscula 1 millim. v^ide, scarce, and scattered over the 

 surface. Alive bright red ; in spirit more dull. The red colour pervades the 

 whole of the cortex ; the pulpa is dull white. Cortex 3 millim. thick. No 

 subdermal cavities. Inhalant pores in the depressions between the tubercles. 

 The small inhalants form a few anastomoses ; they measure only 0*03 

 millim. in diameter, and pervade the cortex in an irregularly radial direction, 

 being much and irregularly curved. The pulpa is very dense. Most of 

 the canals in it extend in a radial direction. 



Skeleton. — Central supporting sphere 4 millim. in diameter. Eadiating bundles 

 0*7-l millim. thick, much expanded in the surface-tufts, the margins of which 

 are in contact, so that the depressions between them appear as sharp narrow inci- 

 sions. — (1) Megasclera. Styli or strongyla. Straight, spindle-shaped ; the greatest 

 thickness near the proximal end ; measuring 2*5 x 0-025 millim. The distal 

 end generally the narrower of the two ; difference in thickness between the tu o 

 ends, 1 : 3. The points of the styli are remarkable for the abrupt manner in 

 which they taper, like a Eoman sword. Sometimes a terrace-like diminution 



