LEUCOKTIS. — LETJCA-NBEA. 



9 



gastral surface have the same size as the vents, measuring 2-4 millim. in dia- 

 meter. The exceptionally extensive gastral cavity has been mentioned above. 

 Skeleton.— (!) Triact Sjiicules. These form the bulk of the skeleton. 

 Two varieties of them are found :— (A) Dermal triacts : the rays of these do 

 not lie in one plane, but are disposed like the edges of a low triangular 

 pyramid. They are equiangular, and the rays slightly curved concave to the 

 pyramid. The rays measure O'lG x 0-01 millim., are conic, and pretty sharply 

 pointed. (B) Triacts of the Parenchyma : Equiangular ; the rays lie in one 

 plane and measure 0-36 x 0-02 millim., are conic and sharp -pointed. The rays 

 of adjacent spicules are parallel and join in such a manner that the ray of the 

 one spicule which points one way is joined for the greater part of its length to 

 the ray of the adjacent spicule which points the opposite way. In this respect 

 our sponge is similar to Am];jlioriscus.—(^2) Diact Spicules. These are not very 

 numerous, imbedded in the outer surface of the sponge, and vertical to it. They 

 project slightly beyond the surface. They are curved, more so near the outer 

 end than proximally. The distal end is very abruptly pointed, like a Eoman 

 sword. The tliickest portion of the spicule is situated just below the outer 

 end. The proximal part is slightly conic and rounded at the end. These 

 spicules measure 1-20 x 0-04 millim. 



Geogeapuical Distribution. — East coast of Australia (Ramsay). 



Genus LEUCANDRA. 

 Leuconidse with diact, triact, and tetract spicules. 



Nearly identical with Haeckel's genus Leucandra. 



Leucandra meandrina, Lendenfeld. 



Lexicandra meandrina, E. von Lendenfeld, " A Monograph of the Australian 

 Sponges. — Part III.," Proceedings of the Linnean Society of New South 

 Wales, vol. ix. part 4, p. 1128 (1885). 



A solitary, cylindrical, tubular sponge, which attains a length of 120 and a 

 diameter of 25 millim. The dermal surface is smooth, without projecting spi- 

 cule-rays ; the gastral surface and also that of the larger exhalant canals appears 

 hairy or velvet-like. The outer surface is very uneven, and bears an intricate 

 meander-like sculpture in high relief. The gastral cavity is cylindrical, and the 

 thickness of the body-wall is very different in difl'erent parts in consequence of 

 the above-mentioned surface-sculpture. The canal-system is rather peculiar ; 

 there are no lacunose extensions of the inhalant canals, no subdermal cavities. In 

 the gastral part of the body-wall we meet with very regular longitudinal canals of 



