340 



POLYCHAETA 



in formation, and has a circular aperture. The worm itself is 



about 



inches long. 



The horny operculum is conical, with 

 its base upwards, fringed 

 with short processes. 20 

 fathoms in the North 

 Sea and Mediterranean ; 

 also from 275 fathoms 

 off the west coast of 

 Ireland. 



Pomatoceros triqveter 

 L. The white shell is 

 adherent, with a distinct 

 keel along its upper 

 surface ; the aperture is 

 overhung by a spine. 

 The tubes are abundant 

 everywhere, attached to 

 rocks, stones, shells, etc., 

 between tide-marks and 

 down to 18 fathoms. 

 The animal is very 

 handsome, the thorax 

 being deep blue, the 

 abdomen red in the 



whitish ill the 



Flc.183.-Agroapoftuhesof,S^^ W m/ CW farfeL. f 



from the mouths of two of which the animals are ripe male. The branchiae 



protruding, that on the right being seen from l,. irr - ( l niu ] nnrtp<l 



above, bf, The gill plume ;,*, thoracic membrane ; <lle ^lired autl ^potted 



op, operculum ; op\ corresponding gill filament with blue, Orange, and 



' 



of the opposite side ; (, tube. 



Aitinuii.) Nat. ize. 



(From Ouvier' 



, . ,, , 



white; the operculum 

 is calcareous, and fur- 

 nished with a couple of horn-like processes. 



Filiyramt iinplejca Berkeley is a small worm, but the slender 

 white tubes intertwine and adhere together in masses o or 4 

 inches high, occurring at low tide and down to 18 fathoms in 

 the North Sea and Mediterranean. The animal has only eight 

 gill filaments on each side, one of which on each side is slightly 

 expanded to serve as an operculum. The worm multiplies by 

 transverse division. 



Sftirorbis lorcalis Daudin is a still smaller worm, the tube of 

 which is coiled in a Hat spiral about ^ to -- inch across ; it is 



