SPIKETTA. 



43 



Spiretta raphidiophora, n. sp. 



Irregularly spherical sponges, which are attached by a small base, and attain a 

 diameter of 40-80 millim. Colour in spirit dark brown on the surface, light 

 brown in the interior. The specimens are not well preserved, and no reliance 

 can therefore be placed on this observation. Surface slightly uneven, rough, and 

 hairy. Very few triangular tangential canals form the subdermal cavity. The 

 interior of the sponge is very dense, no canals of any kind are visible there 

 with the naked eye ; with the microscope, very scarce canals, with a circular 

 transverse section and a diameter of 0-08-0-3 millim., can be seen extending 

 irregularly through the sponge. The oscula are scarce and very small, 0-5 

 millim. in diameter. 



Slcdeton. — This species is very rich in spicules. The supporting spicules 

 form thick bundles, which radiate from the centre and take up the greater part 

 of the body ; the interstices are filled up with monact and spiral microsclera. 

 The radial bundles are composed of large styH and a few tetracts, in which 

 the tangential rays are very small. Besides these there are tetract velar 

 spicules projecting beyond the surface of the sponge. — (1) Tetract Megasdera. 

 round below the surface ; absent in the interior. Angle between the centri- 

 petal and tangential rays <90°; centripetal ray=lxO-01 millim., straight, 

 conic, and pointed ; tangential rays curved, anchor-like, 0-08 x 0-008 millim., 

 sharp-pointed ; two equal, the third sometimes absent, sometimes dissimilar to 

 the other two, and sometimes the three tangential rays of uniform shape 

 and size. — (2) Tetract Velar Spicules. In every respect similar to the tetract 

 supporting-spicules, and projecting 0-3 millim. beyond the surface. — (3) Monact 

 Meijasclera. Eorming the bulk of the bundles in the interior and also of the 

 cortex. (A) Styli 0-6 x 0-07 millim., straight, cyhndrical, conic and rounded at 

 one end, and sharp-pointed at the other. (B) Oxea straight, spindle-shaped, and 

 sharp-pointed, measuring 3-4x0-05 millim.— (4) Monact Microsclera of the 

 Cortex. Abundant, straight or curved, 0*4 x 0-003 millim., rounded at each end.— 

 (5) Monact Microsclera of the Interior. Scattered irregularly throughout the 

 sponge ; oxea 0-24 x 0-02 millim., very slender, and sharp-poiuterl at each end. 

 — (6) Sjjircd Microsclera ; very abundant, particularly in the cortex, forming 

 1 or l|-2 regular spiral turns ; very small, measuring 0-014 x 0-0008 milHm. 



GEouKArHiCAL DisTBiBUTiON. — East coast of Austraha : Port Jackson 

 (^llanisaij). 



Spiretta porosa, n. sp. 



Irregularly spherical sponges, which attain a diameter of 50 millim., with a 

 circular, slightly depressed zone on the upperside, in which numerous large 

 (iseula are situated: these are oval, and measure 8 x 3 millim. iji diameter. 

 Surface hairv and rather uneven, in consequence of the projection of the centri- 



