422 THE ANNELIDA POLYCHAETA. 



ii. With less than four pairs or groups of branchiae. 



j. Branchiae subulate as in tj^jical ampharetids, three pairs. 



Eulhelepus Mcintosh. 

 jj. Branchiae cirrLform. 



k. A single pair of branchiae Prototheleptis Verrill. 



kk. Three pairs of branchiae Streblosoma Sars. 



gg. Setae beginning on the third somite. 



h. First three somites with large lateral foliaceous lobes, on the last forming a lobe 

 across dorsum (uncini with but single crenulus and single series of denticles at 

 vertex) . 



i. Brancliiae arborescent, a single large pair Thelepella, gen. nov.^ 



ii. Branchiae each consisting of 3 or 4 filaments united at base, three pairs. 



Thelepides Gravier. 

 hh. First somites with no such lateral foliaceous lobes. 



i. Uncini beginning on the fourth somite; branchiae branched. .A'^aneca Chamberlin. 

 ii. Uncini beginning caudad of the fourth somite; branchiae simple. 

 j. Uncini beginning on the fifth somite. 



k. Uncini in part in double series; capillary setae with apex dentulate. 



Neole.pea Hessle. 

 kk. Uncini in all cases in single series; capillary setae with apex entire. 



Thelepus Leuckart. 

 jj. Uncini beginning on the eleventh somite. 



Capillary setae on only fifteen somites Parathelpus Caullery. 



ec. Prostomium forming a large upjier lip giving rise to numerous tentacles (branchiae none or a 

 single quadripartite pectinate one). 

 Uncini of thorax rostrate, of abdomen avicular or else absent from thorax or from entire 



body (branchiae none) Pohjcirrinae. 



d. Uncini none. 



/. Notopodial setae present (six pairs of fasciae) Lysilla Malmgren. 



//. No setae at all present Hauchiella Levinsen. 



dd. Unctni present. 



c. Notopodial capillary setae present to posterior end of body .\.phl ebina Quatrefages. 



ee. Capillary setae limited to anterior region of body. 

 Neuropodia absent from thorax. 



/. Neuropodial setae needle-like Aniaca Malmgren. 



//. Neuropodial setae unciniform Polycirrus Grube.-' 



aa.  No ventral plates developed (Trichobranchidae of Hessle). 



h. With two or three pairs of filiform branchiae; uncini of thorax rostrate, of abdomen avicular. 



Trichuhranchinae. 

 c. With three pairs of discrete liranchiae which lack an upper folded part; no chitinous stomach. 



Trichohranchus Malmgren. 

 cc. With two pairs of discrete branchiae, with an upper, more or less folded, part; a chitinous 



stomach Odobranclius Marion and Bobretzkj'. 



66. Branchiae grown together into one or two bodies or absent; uncini of thorax rostrate, of abdomen 



pectiniform Tercbellidinae . 



c. Branchiae none Aponohranchxis Gravier. 



cc. Branchiae pre,sent. 



d. Branchiae united into two groups or bodies Ampharetides Ehlers. 



dd. Branchiae united into one body Terebellides Sars. 



The classification outlined in the key is based primarily upon that proposed 

 by Malmgren in 1865 (Ofvers. K. vet. akad. Forh., 1865, p. 372 et seq.) the five 

 subfamihes being those defined by that worker under the names Amphitritea, 



• Genotype, Terebella cetrata Ehlers. 



2 Cf. Zool. bidrag fr&n Uppsala, 1917, 5, p. 66, 129, etc. 



