10 LEUCANDRA. 



an oval transverse section ; the short axis of the ellipse is situated radially. The 

 thickness of the body-wall is 1-8-2-1 millim., and the gastral cavity is very large 

 accordingly. The longitudinal canals measure, on an average, 0-7 x 1'2 millim. 

 These exhalent, wide, collecting-canals open separately into the gastral cavity, 

 without forming anastomoses or lacunes. The remarkable gastral tetract 

 spicules clothe these canals in the same way as the gastral cavity itself, so 

 that they make rather the impression of branches of a ramified gastral cavity 

 than of exhalant canals. 



Spicules. — The skeleton consists of gastral tetract spicules with a very 

 elongated, protruding centripetal ray, parenchymal triacts of two kinds, and 

 parenchymal, radially situated, and slightly protruding large diact spicules. 

 The (/astral tetrads are sagittal and regular. The centripetal ray measures 

 from 0*07 to 0*28 millim. in length ; the longer ones predominate, they have 

 a very constant basal thickness of 0*005 millim. The tangential rays lie in one 

 plane, which is vertical to the centripetal ray. They, and also the angles 

 between them, are equal. Like the centripetal ray, the tangential ones are 

 quite straight or slightly and irregularl}'- curved at the distal end ; they 

 measure O'lS x 0*005 millim. All rays are cylindrical and pointed. The triads 

 of the iMrencliyma are regular or slightly irregular, never sagittal, and stout or 

 slender ; the stout ones predominate throughout ; the slender ones are more 

 numerous towards the outer surface. The rays of the stout triacts , measure 

 0*28 X 0-021 ; those of the slender ones have the same length, but are only 

 0*007 millim. thick. Among the triacts there are also a few small tetracts 

 with rays corresponding to those of the slender triact spicules. Transition- 

 forms between these tetracts and the slender triacts are present in great 

 abundance. Transition-forms between the slender and the stout triact spicules 

 do not exist. The diad spicules are spindle-shaped and pointed at both ends ; 

 they measure 1*5 x 0*035 millim., and are rare. Around the osculum there are 

 no differentiated spicules. 



Geogbaphical Distribution. — East coast of Australia: Port Jackson 

 {Lendenfeld). 



Leucandra cataphracta, Haeckel. 



Leucandra catapJiracta, E. Haeckel, Die Kalkschwamme ; eine Monographic, 



Band ii. Seite 203 (1872). 

 Leucandra cataphrada, E. v. Lendenfeld, " A Monograph of the Australian 



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



Wales, vol. ix. part 4, p. 1129 (1885). 



The sponge consists of a solitary person, which has an elongate, cylindrical, 

 fusiform, or flattened shape. A slender peduncle and a narrow oscular 



