858 



SPONGES AND ZOOPHYTES 



pin or may carry three or more diverging points which sometimes 

 curve back so as to form hooks. When the spicules project from the 

 horny framework they are usually somewhat conical in form, and 

 their surface is often beset with little spines arranged at regular inter- 





B 



rn.c. 



Fin. (>">-]. A, section through I'lnilcrllin r< 'nl iJtiLriiin, var. connexida, taken at right 

 angles t,ci the surface, to show the- arrangement of the parts of a. sponge : /i, pores 

 on the snrt'iiee |e:nlin;j to if, tlie inlialiinl canals, then to the flagellated chambers, 

 /'<, Mild thence to the exhalant CMluils, /'f, to o, the oseiila, in the derniMl meinlirane. 

 dm. I'}, nion- highly magnified view of (lie internal portion ichoanosome) of 

 Axiliella paradoXd li'.M) : me, so-called mesodennal cells. Other letters MS in A. 

 (After Ridley and Bendy.) 



