212 F. Chapmaii: 



together in a closely fasciculivte manner. The examples now 

 figured measure as f()llf)vv.s : — (PI.XVTr., I<'i^. 1). Len;L,'th, 2.346 

 mm.; greatest breadth, 0.0721 mm. A slightly sig-moidal 

 spicule (PI. XVII., Fig. 2), length, 1.6. mm. 



Protriaene. — A variety v/ith straight cladi, 0.423 mm. long ; 

 length of cladi, 0.154 mm. Cladi making ajn angle of 48 deg. 

 with the produced rhabdui^. A variety with curved cladi having 

 a length of 0.481 mm. : cladi forming an angle of 30 deg. A 

 variety with the cladi sigmoidally cun'ed, 0.461 mm. in length; 

 width of chord, 0.25 mm. 



Dichotriaene. — Rays of the trivium lying nearly in the same 

 plame. That which would ordinarily be considered the prin- 

 cipal actine is almost entirely suppressed. An example from 

 this sponge has an extreme diameter of 0.4S mm. 



Microstrongyles.-- Length of an average example, 0.423 mm. ; 

 width, 0.0384 mm. 



The ?spiraster. — Length. 0.346 mm. 



Microxea with spine.- in whorls. — Length, 0.25 mm. ; width, 

 0.1 mm. 



Spheraster. — Diameter of centrum, 0.0576 ; length of longest 

 rays. 0.0432 mm. 



An ellipsoidal sterraster. — Longer diameter. 0.153 mm ; 

 i-horter diajmeter, 0.11 mm. 



A sanidaster with a length of 0.336 mm. 



Class — Anthozoa. 



Family — Astraeidae. 



Genus — Heliastraea, Ed. iuid Haime. 



HeMastraea tasmaniensis, Duncan. 



H. tasmaniensis, Duncan, 1876, Quart. Jnurn. Cleol. Soc, Vol. 

 XXXIL, p. 342, PI. XXIL, Figs. 1-3. 



Obi-ervations. — An examplo of this coral occurs as a cast in 

 ironstone, and is sufficiently well preserved to furnish a sharp 

 wax iinpressiuii, clearly showing tlic number of primary 

 and secondary stpta ar.d their quaternary arrangement, as 

 described by Duncan. The corallum measures about 4 cm. 

 square, whilst the oaliees have n diameter of about 4 nnn. 



