324 A MONOGRAPH OP TIIR AUSTRALIAN SPONGES, 



Fig, 17._Aulena villosa. R. v. L. Margin of a particularly large sand 

 grain of the skeleton from a specimen macerated in fresh water. 

 Magnified 400:1. {H). Horny fibre. (M). Horny membrane. 

 [A). Axial canal of the horny fibre. 



Fig. 18.— Aulena villosa. R. v. L. Transverse section through a horny 

 fibre just below the point of growth. Osmic-acid alum oarmin 

 specimen. Magnified 1,000:1. (^). Axial canal. (/?). Stratified 

 horny substance. [S). Coating of spongoblasts. {B). Tissue 

 coating. Transverse section through the longitudinal, spindle- 

 shaped tissue cells. (B'). A tissue thread consisting of spindle 

 shaped tissue cells which attaches itself to the tissue coating of 

 the horny fibre 



Plate XXXI. 

 Fig. 19.— Aulena villosa. R. v. L. Section through the outer portion of 



the sponge. Alcohol-alum-carmin specimen. Drawn from a thick 



section. Magnified 10:1. {L). Lacunose tissue of the vestibule. 



{S). The reticulate body of the sponge itself. (6"). Free portions 



of the sponge body projecting beyond the surface — rounded 



conuli. 

 Fig. 20. — Aulena villosa. R. v. L. Longitudinal axial section through the 



specimen represented in fig. 14. Drawn from a spirit specimen 



cut in two. Natural size. 



Plate XXXII. 

 Fig. 21. — Aulena villosa. R. v. L. Radial section through the distal portion 

 of the sponge. Two conuli are cut through and appear extending 

 beyond the lacunose tissue of the vestibule. Combined picture. 

 Magnified 50:1. 



Plate XXXIII. 



Fig. 22. — Aulena villosa. R. v. L. Skeleton of the distal portion of the 

 sponge. Macerated in fresh water. Drawn from a thick section 

 made by hand. Magnified 50:1. {L). Lacunose system of the 

 vestibule. (S). Portions of the real sponge tissue. (6"). Free 

 projecting portions (conuli.) 



