20 A MONOGRAPH OF THE AUSTRALIAN SPONGES, 



that the whole pavement attains a high degree of firmness. 

 Similar cortical layers are known of many Sponges. No species 

 of Gumminte possesses them so highly developed as this Chondrilla 

 corticata. 



Locality : East Coast of Australia. Port Jackson. 



EXPLANATION OF PLATES. I. to V. 



Fig. 1 . — Bajalus laxus. R. v. L. A specimen of the variety with lobate 

 processes. Natural size drawn from life. 



Fig. 2. — Bajalus laxus. R. v. L. A specimen of the variety with finger- 

 shaped slender processes. Natural size drawn from life. 



Fig. 3. — Bajalus laxus. R. v. L. Transverse section through a process of 

 the variety with slender outgrowths, 1:20. An outer trabecular 

 reticulate zone, (d) can be distinguished and large conic inhalent 

 Canals (i.) The exhalent Canals (e) are much narrower, extending 

 more or less radially, these are cut obliquely, and therefore appear 

 very oval in the section. The interior (I) appears lacunose, and can 

 be considered as a wide Canal (like the central tribe of the 

 Syconidse) traversed by threads of tissue (t. ) 



Fig. 4. — Bajalus laxus. R. v. L. Distal part of the transverse section 

 through a slender process 1:450. The inhalent pores {p) are covered 

 by a thin perforated plate externally, (a) which is perforated by 

 numerous small pores (p), leading into the pore (P.) Below the 

 outer skin (6) a wide sub-dermal cavity extends all round the 

 Sponge (/■), which is traversed by numerous anastomosing and 

 repeatedly ramified threads (c). All these parts are covered 

 by flat Ectodermal Epithelium cells (e). In the skin and in the 

 Sub-dermal threads we find amoeboid wondering cells (d.) In the 

 skin below the outer surface glandcells (g), the water flows partly 

 direct from the Sub-dermal cavity, and partly by way of large 



