MALDANIDAE. 409 



Key to the Subfamilies and Genera. 



a. Cephalic plate absent. 

 6. Nuchal organs forming a semicircular bow. 



c. Collar-somite and double rows of uncini present Rhodininae. Rhodine Malmgren. 



cc. No collar-somite or double rows of uncini present Lumbriclymeninae. 



d. Anus terminal. 



e. Somites very numerous Praxillura Verrill. 



ee. Somites not very numerous Lumbridymene M. Sars. 



dd. Anus dorsal Noloproclus Arwidsson. 



bb. Nuchal organs forming a more or less open bow, or nearly straight Nichomachinae. 



c. Anal cirri present Nicomache Malmgren. 



d. Floor of anal cup strongly inclined Subgen. Loxochona Arwidsson. 



dd. Floor of anal cup but little inclined Subgen. Nicomache sens. str. 



cc. No anal cirri Petaloprocttis Quatrefages. 



aa. Cephalic plate present. 



b. Crochets in neuropodia and capillary setae in notopodia as usual; all but anterior parapodia on 

 the posterior region of somites. 



c. Anus terminal Euclymeninae. 



d. Anal cirri numerous, but none strictly ventral Proclymenini. 



e. Free cephalic margin strongly developed all around Maldanella Mcintosh. 



ee. Free cephalic margin absent, or but weakly developed and wholly lacking posteriorly. 



/. Four spine-bearing somites Proclymene Arwidsson. 



ff. Three spine-bearing somites Isocirrus Arwidsson. 



dd. Anal cirri none, or else with one strictly ventral. 



e. A triangular glandular area on the ventral surface of the eighth setigerous somite. 



Leiochonini. Leiochone Grube. 

 ee. No such triangular glandular area beneath on the eighth setigerous somite. . .Ev^ylmenini. 

 f. Eighth setigerous somite short, parapodia near or in front of the middle. 



g. Anal cirri none or few Microclymene Arwidsson. 



gg. Anal cirri numerous. 



h. Nuchal organs short Pseudoclymene Arwidsson. 



hh. Nuchal organs not especially short. 



i. With lateral glandular areas in front of first setigerous somite. 



Heteroclymene Arwidsson. 

 ii. No lateral glandular areas in front of first setigerous somite. 



j. With a funnel-shaped anal depression, from the bottom of which the cone arises. 



k. Numerous ventral setae present on somites 1-3 Paraxiothea Webster. 



kk. Ventral setae on somites 1-3 occurring singly Euclymene Verrill. 



jj. With no funnel-shaped anal depression Iphianissa Kinberg. 



ee. Eighth somite long, with its parapodia posterior in position Caesicirrus Arwidsson. 



cc. Anus dorsal. 



c. Uncini all in single vertical rows Maldaninae. 



d. Cephalic keel pronounced, long and high Maldane Grube. 



dd. CephaUc keel weak Asychis Kinberg. 



cc. Uncini on some somites in two or three rows Sonatsinae, subfam. nov. 



Cephalic keel pronounced; no dorsal glandular area on somite 5 Sonatsa, gen. nov. 



bb. Crochets in a single series in all notopodia, the neuropodial setae exclusively capillary; parapodia 



anterior in position on all somites Heteromaldaninae, subf. nov. 



Heleromaldane Ehlers. 



In this key I have adopted, in general, the classification developed by .Arwids- 

 son in his excellent monographic study of the family (Zool. jahrb. SuppL, 1907, 

 9, heft. 1). 



