SABELLIFORMIA 



337 



which is frequently notched, so that a lateral and a ventral lol>e 

 on each side may lie distinguished (Fig. 133, B, p. 261). The 

 thorax consists of nine segments, and is provided with ventral 

 " gland shields," which are continued along the abdomen, where 

 they are subdivided into two by a ciliated " faecal groove," which 

 sometimes bends to one side on reaching the thorax, and may 

 extend forwards along the dorsal surface to the head : this groove 

 serves to carry the faeces out of the tube. The gill filaments 

 are always provided with secondary processes, and may be pro- 

 vided with compound eyes. 1 The tubes of the Sabellidae are 

 always of fine mud or of sand. 



Sabella pavonia Sav. is about 10 to 12 inches long and 

 about inch across ; the tube of fine mud is considerably longer 

 and embedded deeply in the mud, with its free end projecting to 

 some 2 or more inches, where it serves for the attachment of 

 seaweed, Polyzoa, Hydrozoa, etc. The colour of the animal is 

 orange-brown ; the gills, which are about 1^- inches long, are 

 green (due to contained blood) marked with more or less extensive 

 brown or purple-brown spots, which may even hide the green 

 tint. There is a pair of dark filaments arising between the 

 dorsalmost gill filaments, 

 which have been errone- 

 ously regarded as " pro- 

 stomial tentacles " ; they 

 are, in fact, prolongations 

 of a peculiar membrane or 

 lip round the base of the 

 gills, which bounds a groove 

 leading to the mouth. 

 These lip -processes (Fig. 

 133, B, /) occur in other 

 Sabellids. Atlantic, North 

 Sea, and Mediterranean. 



Branckiomma vesic'U- 

 losum Mont, forms a Sandy FIG. 182. A, A gill filament of liranchiommo : 

 , , T , . , , B, of Dasiichoite. , Axis ; /; secondary ttla- 



tube near low tide-mark. mc ut s ; ^, eye ;.--, dorsal up r c-ulice s . 

 The animal, measuring G-7 



inches, is rich brown, darker anteriorly, abundantly speckled with 

 white ; the ventral surface is pink ; the gills are green or olive- 



1 Andrews. Jutini. Mvrph. \. 1891, p. 271. 

 VOL. II 7. 



