SPONGES 



45 



Fio. 40. 



Histological elements, a, collencytes from Thenea muricata ; b, chondrenchyme, from 

 cortex of Corticium oaiwfota&ntm (the unshaded bodies are microscleres) ; c, cystenchyme, from 

 Pachymitisma Johnstonii (partly diagrammatic); d, desmaeyte, from Dragmastra Normani; e, 

 myocytes in continuity with collencytes, from Cinachyra lurhata ; f, thesocyte, from Thenea 

 muricata ; g, choanocyte, from Sycon ruphanus; h-n, scleroblasts ; h and i of rhabdi, from 

 Cranielln cranium; j, of a triaene, from Stdletta ; /,-, of a tetracladine desma, from Theonella 

 winhnel ; I, of a si^maspire, from L'ranieUa cranium : m, of a dj-agma, from Diayrivga <lhaimilis ; 

 ns, of a sterraster, from Geodia barrctti. (Figs, ft and <j after Sclmlze, the rest after Sollas.) 



