22 Catalogue of Chaetopoda 



A. PHAJSTEROCEPHALA (continued). 



Spioniformia. Capitelliformia. 



Spionidae. Capitellidae. 

 Polydoridae. 



Chaetopteridae. Scoleciformia. 



Magelonidae. Opheliidae. 



Ammochandae. Maldanidae. 



Arenicolidae. 



Terebelliformia. Scalibregmidae. 



Cirratulidae. Chlorhaemidae. 



Terebellidae. Sternaspidae. 

 Ampharetidae. 

 Amphictenidae. 



B. CRYPTO CEPH ALA. 



Sabelliformia. Hermelliformia. 



Sabellidae. Hermellidae. 



Eriographidae. 

 Amphicorinidae. 

 Serpulidae. 



Although this classification has many good points it is not 

 without defects; for instance, the great sub-order Nereidiformia, 

 which contains about half the number of families and of genera 

 of Polychaeta, is rather unwieldly, and not entirely homogeneous. 

 The families Maldanidae, Arenicolidae and Scalibregmidae, and pos- 

 sibly the Opheliidae, contain series of more or less closely related 

 worms ; associated with these, in the sub-order Scoleciformia, are the 

 Chlorhaemidae and Sternaspidae, which stand considerably apart 

 from the preceding quartette ; but if the two latter families are not 

 included in the Scoleciformia they cannot be referred to any other 

 sub-order, and the formation of one or two new sub-orders would be 

 required for their reception. 



In Prof. Hatschek's classification 1 the Polychaeta are separated 

 into two main subdivisions namely, the Cirrifera those in which 

 parapodial cirri are present, and in which the homonomy of the 

 segments is little disturbed and Acirra which are without clearly 

 marked parapodial cirri and in which heteronomy of the external 

 and internal structures indicates a division into regions. This 

 classification may be tabulated thus 



A. CIRRIFERA. 

 1. Spiomorpha. 



Spionidae. Appendices : Chaetopteridae. 



Ariciidae. Pherusidae. 



Opheliidae. 



1 Lotos, xiii (1893), p. 123. 



