34 ART. 7. — T. TJIMA : HEXACTIXELLIDA, IV. 



indistinctly visible through the gastral layer, may be 2 mm. wide. 

 In tlie wet state the sponge-wall is rather firm Imt can he 

 easily torn off. When dried it is of a light, delicate and friable 

 texture. 



Spiculation. 



The j)arencliym(dia consist of diactins only, — oxydiactins as 

 a rule. Tliese comprise all sizes from the large, elongate-spindle 

 shaped or bow-like principalia down to the shorter and very 

 much thinner comitalia. They are somewhat closely felted to- 

 gether in forming the parenchymal mass. (See PI. YL, fig. 17). 



The principalia, which occur rather numerously, may attain 

 a leno-th of 10 mm. and a thickness of 120 n. in the middle. 

 They are smooth all over, even near the sharply pointed ends. 

 The smaller parenchyraalia, leading down to comitalia of only 

 10 // thickness, often show an indication of an annular swelling at 

 the center and are sparingly beset with ol solete microtubercles 

 at the ends, which taper to a point instead of being slightly 

 swollen as usual. — Certain small diactins on the outer and inner 

 surfaces of the choanosome are formed into thin strands and go 

 into the support of the dermal and gastral layers, more especially 

 of the latter. 



Hypodermal oxypentaetUis are abundantly present. The rays 

 are all smooth throughout and always regularly cruciate in dis- 

 position. They are never very large, the paratangential axial 

 length not exceeding 3 mm. The unpaired proximal ray is 

 usually more than three times as long as the paratangential in 

 the same spicule. Breadth of rays at base, as much as 55 IK — 

 No pentactins occur as hypogastralia. 



