SPONGES 



45 



FlO. 49. 



Histological elements, o, collencytes from Thenea murimta; b, chondrenchyme, from 

 cortex of Corticium candelabrum (the unshaded bodies are microscleres) ; c, cystenchyme, from 

 Pachymatisma Johnstonii (partly diagrammatic); d, desmacyte, from Dragmastra Normani; e, 

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

 muricatu; g, choanocyte, from Sycon raphanus ; h-n, scleroblasts ; h and i of rhabdi, from 

 Cr/niiella cranium; j, of a triaene, from Stelletta ; /.', of a tetracladine desma, from TheoneUa 

 vinhfiel ; I, of a sigmaspire, from Craniella cranium : m, of a dragma, from Disyrirtga dinsimilis; 

 us, of a sterraster, from Geodia barrctti. (Figs, b and g after Schulze, the rest after' Sollas.) 



