174 



ALFBED GIBBS BOUKNE. 



— thorax and abdomen ; the setae are simpler than in other 

 sabellids, and the coprajjoo^al <;roove is absent. 



A comparison of the heads in these genera seems to throw 

 considerable light upon the nature of the processes of the head 

 in the Serpulidae. 



In Amphiglena^ the prostomium remains well developed, bear- 



A. Diagram of bead of Ampbiglena, dorsal view. 



B. Diagram of head of Fabricia,, dorsal view, prost. Prostomium. prosi. 



tent. Prostomial tentacles. /. Peristomial somite, coll. Peristomial 

 collar, oc. Eye-spots, and. Otocyst. After Claparede. 



ing lateral pigment spots and a pair of tentacles. It is difficult 

 to make out the nature of the palps from Claparede's figures ; 

 there are two ventral processes which may represent them. 

 The branchiae which, according to Claparede, vary in number, 

 from eight to twelve, have taken up such a position as to form 

 a circular crown, and bear along their whole length a series of 

 short, opposite, secondary filaments. 



The branchiae appear to spring from the peristomium. 



In Fabricia,2 also, prostomial tentacles may be definitely 

 determined. 



1 Claparede, ' Glanures Zootomiques parmis les Ann^lides de Port Vendres,' 

 p. 32, pi. 3. 



3 Claparede, loc. cit., p. 3G, pi. 3. 



