422 THE ANNELIDA POLYCHAETA. 



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



j. Branchiae subulate as in typical ampharetids, three pairs. 



Euthelepus Mcintosh. 

 jj. Branchiae cirriform. 



k. A single pair of branchiae Protoihelepus Verrill. 



kk. Three pairs of branchiae Strehlosoma 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. Branchiae 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 .. iVanem 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. 



Neolepea 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 Parathelputs CauUery. 



fc. Prostomium forming a large upper 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) Polycirrinae. 



d. Uncini none. 



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



//. No setae at all present Hanchiella Levinsen. 



dd. Unctiri present. 



e. Notopodial capillary setae present to posterior end of body Aphl ebina Quatrefages. 



ee. Capillary setae limited to anterior region of body. 

 Neuropodia absent from thorax. 



/. Neuropodial setae needle-like Amaea Malmgren. 



//. Neuropodial setae unciniform Polydrrus Grube.'- 



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



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



Trichobranchinae. 

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



Trichobranchus Malmgren. 

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



stomach Octobranchus Marion and Bobretzky. 



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



pectinif orm Terebellidinae . 



c. Branchiae none Aponobranchus Gravier. 



cc. Branchiae prasent. 



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 

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



1 Genotype, Terebella cetrala Ehlers, 



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



I 



