28 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 7 



Subfamily Lepidonotinae Seidler 

 Key to Genera of LEPIDONOTINAE herein considered 



1. With 12 pairs of elytra 2 



1. With 15 pairs of elytra EULAGISCA 



1. With 18 pairs of elytra HALOSYDNA 



1. With more than 18 pairs of elytra 4 



2. Elytrophores with branchiae . . . CHAETACANTHUS 



2. Elytrophores without branchiae 3 



3. Notopodia with two kinds of setae, including some which are 

 smooth, lancet shaped THORMORA 



3. Notopodial setae of one kind, ornamented with transverse rows 

 of serrations LEPIDONOTUS 



4. Prostomial antennae inserted subterminally ; neuropodial setae 

 few, stout, falcate, the serrations obscure or absent .... 

 ARCTONOe 



4. Prostomial antennae inserted distinctly terminally; neuropodial 

 setae numerous, not unusually stout, transverse serrations usu- 

 ally distinct LEPIDAMETRIA 



Genus CHAETACANTHUS Seidler 



Resembles Lepidonotus Leach in segmental and elytral counts; 

 elytrophores with branchial appendages. Dorsal setae fine, hair-like, 

 numerous, much as in Iphione Kinberg. Several species have been de- 

 scribed in this genus, but all are thought to be identical with C. mag- 

 nificus (Grube) (Seidler, 1924, p. 97). 



Chaetacanthus magnificus (Grube) 



Iphione magnifica Grube, 1875, p. 51. 

 Polynoe branchiata Treadwell, 1902, p. 186, figs. 5-7. 

 Lepidonotus (Physalidonotus) barbatus Augener, 1910, pp. 244-246, 

 figs. 4-6. 



Chaetacanthus magnificus Seidler, 1924, pp. 97-98; Monro, 1928a, p. 

 558. 



