BY R. VON LENDENFELD, PH.D. 13 



Below each group of pores we find an extensive hollow (on the 

 section). In comparing the different sections of a continuous series 

 it is easy to ascertain that these hollows are the expression of 

 transverse sections of tangentally extended wide lacunose canals 

 (fig. 7-8). Below the zone of these smaller tangental lacunes we 

 find a system of larger ones similar in shape and distxibution. The 

 canals of the outer zone communicate with one another by means 

 of very rare and minute pores (fig. 8), and also with the larger 

 lacunes below by means of similar pores which in consecpience of 

 their paucity and smallness are very hard to find (figs. 7-8). 



All these lacunes lie so close to one another, that only narrow 

 walls of tissue remain between them (fig. 7.) 



The average diameter of the lacunes in the outer zone is 0-05, 

 of those in the lower zone 0"2mm. The lucunose zone has a 

 thickness of 0*4 mm. 



Below this no lacunes are found in the cortex, except a few 

 very distant and large irregular tangental canals (fig. 6), which 

 collect the water from the small communicating outer lacunes. 

 These canals have very irregular transverse sections and an 

 average diameter of 1 mm. The cortex is of about equal thickness, 

 so that the whole thickness of it is taken up by these large inhalent 

 canals. The lower side of these large tangental canals lies in the 

 surface, which divides the cortex from the Pulpa of the Sponge. 



From this lower side numerous canals originate, which are 

 cylindrical, and follow a moi-e or less radial direction. Repeatedly 

 ramified, they become smaller and smaller the further we penetrate 

 into the Sponge. 



Around the final coecal and narrow ramifications the ciliated 

 chambers, which are spherical, cluster. They have a diameter of 

 0-05 mm., and do not appear to be very numerous. The inhalent 

 pores could not be found. The exhalent opening is small and 

 circular. Regarding their shape and position they do not difier 

 from those of Chondrosia reniformis, and I refer to F. E. JSchulze's 

 (1) description. 



(1) F. E. Schulze. Die Familie der Chondrosidaj. Zeitschrift fur 

 wissenschaftliche Zoologie. Band XX [X. Seite 107-108. 



