TEREBELLIFORMIA 



327 



" cephalic tentacles," probably peristomial, and similar to the 



"tentacular filaments " of Dodecaceria ; (2) a pair of filamentous 



gills (dorsal cirri) on the first chaetigerous 



segment ; (3) a pair of large green nephridia 



in the anterior segments. The describer 



placed it amongst the Spionids, but the 



above and other features point to Cirratulid 



affinities. 



FAM. 2. Terebellidae. The body is cylin- 

 drical, and generally larger in front than 

 behind. The prostomium is generally 

 flattened, and forms a mobile upper lip, 

 which always carries a transverse series of 

 many tentacles; it may bear "eye -spots," 

 but never palps ; the lower lip is formed by 

 the peristomium. There are one to three 

 pairs of gills, which are usually more or less 

 branched, on as many segments. 1 



The chaetigerous lobes are small ; the 

 dorsal ones contain capillary chaetae, which 

 are frequently confined to the anterior 

 segments, whilst the ventral chaetae are 

 uncini. The ventral surface of the anterior 

 segments is thickened by glands which secrete FlG - 

 the mucus employed in tube -building; the 

 number of these " shields " and of the dorsal 

 bundles of chaetae have to be noted in iden- 

 tifying the worms. There are one to three 

 pairs of large anterior nephridia. A very strong "dia- 

 phragm " usually more or less pouched cuts off this anterior 

 region of the body-cavity from the rest, and is the only com- 

 plete septum in the body; from three to twelve pairs of 

 small generative ducts occur behind it. The family is tubi- 

 colous, foreign materials being generally used in the formation of 

 the tube. 



There are six genera which are fairly common round our 

 coast, and their identification may be facilitated by means of 

 the following table * : 



Ramage.) 



1 In some genera there are no gills, e.g. Leaena. 

 3 These characters are not necessarily generic. 



