SERPULAD2E. 



95 



S. intricata. 

 vermicularis. 

 triquetra. 

 contortuplicata. Fig. 149 ; n. s. 



S. serrulata. 

 filiformis. 

 rugosa. 

 Cordineri. 



Spirorbts (Lamk.). As Serpula, but with only six 

 gill-threads, which are pinnate, retractile and radia- 

 ting. Tube coiled in a flat spiral, cemented to sea- 

 weeds and other submarine substances. 



Dextral. 



S. communis. Fig. 150; mag. 1 T « 

 spirillum, 

 granulatus. 

 carinatus. 

 corrugatus. 

 Montagui. 



Sinistral. 



S. heterostrophus. 

 minutus. 

 conicus. 



S. incurvatus. 

 pernus. 

 retortus. 

 annulus. 

 heterocliticus.* 

 : striatulus. 



S. lucidus. 

 reversus. 



Filograna (Berkeley). As Serpula, but with only 

 eight gill-threads, of which two bear a funnel- 

 shaped obliquely-truncate operculum. Tube slender, 

 thread-like, crowded into an irregular mass. 



F. implexa. Fig. 151 



n. s. 



Ditrupa (BerkL). Gills of twenty- two threads 

 in two sets, not rolled spirally, singly pinnate. 

 Tube free, open at both ends. 



D. subulata. Fig. 152; mag. j-. 



