AURICOMAD^E. 91 



Order II. CHJETOPODA. 



Bristles of two kinds, awl-shaped and 

 hooked ; feet with single cirri, or none. 

 No head, eyes, or jaws. Gills on the front Cephalobranchia. 



Bristles of only one kind Mesobranchia. 



Tribe I. Cephalobranchia. 



Bristles of a golden colour, arranged like 

 a crown on the front ; numerous tentacles 

 around the mouth ; gills in the form of 

 combs. Inhabiting a tube composed of 



grains of sand Auricomadce. 



Numerous extensile thread-like tentacles 

 around the mouth ; gills in the form of 

 little shrubs. Tube composed of sand, 

 minute stones, or fragments of shell . . Terebelladce. 



Gills in the form of a coloured fan, with 

 a fleshy tentacle at the base, on each side 

 of the mouth : 



Both tentacles simply pointed, or 

 wanting. Tube almost always mem- 

 branous, mingled with clay .... Sabelladte. 



One of the tentacles expanded into 

 a disk at the tip, which closes the 

 mouth of the tube. Tube solid, calca- 

 reous Serpuladtf. 



Family I. Auricomad^:. 



Pectinaria (Lamk.). Bristles forming two combs, 

 with teeth directed downward. Tube regularly 

 conical, free, formed of grains of sand. 



P. Belgica. Fig. 142; n. s. 

 arenaria 1 

 subcylindrica ? 

 setiformis ? 



