6 LETJCETTA. 



iu sbape to the sagittal oues in the parenchyma, are very numerous ; their 

 unpaired ray is situated radially, and pointed inwards. The paired rays 

 stand nearly vertical on this one and are very variable in size ; always, 

 however, very slender ; they form a dense and hard dermal felt. — The 

 Dermal diact spicules are cylindrical and pointed at both ends, more abruptly 

 at the distal end. They are very slender, and consequently nearly always 

 broken off in preserved specimens. They measure 2-3 x 0-014 millim. These 

 spicules are massed in clusters of from 10 to 15, and they protrude five sixths 

 of their length beyond the surface, on which they stand vertical. The clusters 

 are regularly disposed, and situated at intervals of about 2 millim. from one 

 another. Small linear diacts are also met with in these clusters, 



GEOGKAPniCAL DISTRIBUTION. — East coast of Australia : Port Jackson, on 

 rocky bottom {Lendenfeld). 



Familia LEUCONID^. 



Heterocoela with ramified inhalant and exhalant canals, and with 

 spherical ciliated chambers. The outer surface is not differentiated 

 into distinct poriferous and osculiferous areas. 



This family comprises the Leucones of Haeckel with spherical chambers with 

 the exception of the Teichonidae. 



Genus LEUCETTA. 

 Leuconidae with exclusively triact spicules. 



This genus is nearly identical with Haeckel's genus of that name. 



Leucetta microrrhaphis, Haeckel. 



Leucetta microrrhapJiis, 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. 1117 (1885). 



Leucetta microrrJiaphis (Leucetta primirienia, var. microrr7iap>his), E. Haeckel, 

 Die Kalkschwiimme ; eine Monographic, Band ii. Seite 119 (1872). 



Leucetta primigenia, var. microrrliaplds, S. O. E-idley, Report on the Sponges, 

 Eeport on the Zoological Collections made in the Indo-Pacific Ocean 

 during the Voyage of H.M.S. ' Alert,' 1881-82, p. 482 (London, 1884). 



Dermal and gastral surfaces smooth. Triacts regular. Pays straight, 

 pointed. Numerous small spicules measuring 0-142 x 0-011 millim., and 



