THE SPONGES OF THE WEST-CENTRAL PACIFIC 257 



The shape of the individual sponge of this species may be considered to 

 be a cone 12 cm high, rising from a base 12 cm in diameter to an apical oscule 

 4 cm in diameter, with a smooth sharp rim. It is frequently true, however 

 (as in the type specimen), that two or more individuals of this type grow so 

 close together that their bases coalesce. It is strikingly characteristic of the 

 species that the sides of these cones are deeply furrowed, with furrows about 

 1 cm apart and nearly 1 cm deep but rounded in contours. 



The exterior color in life was dark green, sometimes verging on olive. 

 The interior was regularly lighter and brighter — a very vivid green. The 

 consistency was crisp, stiff, and easily cut. 



Other than the above-mentioned deep furrows, the surface is almost 

 smooth. The pores are on the outside of the sponge and are 30 ju, to 60 n in 

 diameter, not uniformly spaced but occurring often in little groups of two 

 or three almost touching one another. These groups are frequently as much as 

 100 /x to 200 fi apart. They extend over the whole exterior surface. The inter- 

 ior cavity or cloaca extends from the summit almost down to the base of the 

 sponge. The openings into it may possibly be the genuine oscules. These are 

 1 to 2 mm in diameter and 3 to 5 mm apart. 



The ectosome is a very thin, fleshy structure but is underlain by numer- 

 ous small spicules. The endosome is rather like the crumb-of -bread structure 

 found in many Demospongea and is crowded with globular flagellate chambers 

 about 90 jjl in diameter. There are conspicuous inhalant canals (prosochetes), 

 perpendicular to the exterior surface, and there are also conspicuous exhalant 

 canals (apochetes), perpendicular to the cloaca. 



The skeleton comprises only triaxons of two size ranges with very long 

 sharp rays. Of the larger spicules, these are 20 /a by 300 //., sometimes as much 

 as 35 [x by 400 p.. Of the smaller size range, there are some 5 ^ by 75 /i, to 

 10 [i by 100 [i. 



For a Leucetta having only triaxons, no oxeas or tetraxons, the long 

 thin rays are somewhat distinctive. The color scheme is also noteworthy, and 

 particular attention is called to the vertical, very deep, very conspicuous 

 surface furrows. 



ORDER SYCONOSA de Laubenfels (or SYCONIDA*) 



FAMILY LEUCONIIDAE de Laubenfels 



GENUS LEU CON I A Grant 



Leuconia tropica (Tanita) de Laubenfels 



Text Figure No. 181 



This species is not represented by any specimen in the present collection. 

 It was collected in the Palaus (with no further details given), by a Mr. Hiro 

 in 1936 and by a Dr. Abe in 1935. 



* See footnote on page 4. 



