362 



OLIGOCHAETA 



Genera of Perichaetidae. 



KiNBERG (pp. 101-103) distinguished no less than six genera of those species 

 characterised by possessing more than eight setae to each segment; it is possible, 

 however, that some of them might be AcanthodriUdae as defined in the present work. 



These ' genera ' are thus defined by Kinbeeo : — 



Amyntas, n. Lobus cephalicus, e parte superiore anteriore segment! buccaHs 

 formatus, marginibus lateralibus sohs distinctis, segmento illo 

 multo angustior et brevior ; segmenta anteriora posterioribus 

 duplo longiora ; setae radiatim et seriatim collocatae, minutae, 

 laeves, 50-60: nae posteriores magis numerosae. 



NiTOCKis, n. Lobus cephalicus transversus, latus, obtusus, superus, postice arcua- 

 tus, integer; segmenta anteriora et posteriora reliquis longiora, 

 medio carinata ; setae series transversas formantes, parvae, 1 8-53 : 

 nae posteriores magis numerosae ; cingulum nullum. 



Pheketima, n. Lobus cephalicus terminalis, transversus, ad marginem anteriorem 

 superiorem segment! buccalis affixus ; setae radiatim et seriatim 

 positae, segmentorum posteriorum illis anteriorum magis numero- 

 sae ; foramina dorsalia ; cingulum ; tubercula ventralia duo. 



Bhodopis, n. Lobus cephalicus baud distinctus, e margine anteriore superiore 

 segment! buccalis formatus ; orificium oris terminale plicis papillae- 

 formibus instructum; setae radiatim et seriatim positae, minutae, 

 segmentorum posteriorum i41is anteriorum magis numerosae. Tuber- 

 cula ventralia duo in sutura segmentorum obvia. 



Pekichaeta (Schmaeda), ex parte. Setae numerosae, anteriores et posteriores numero 

 aequales. 



Lampito, n. Lobus cephalicus transversus, ovalis, integer ; segmentum buccale 



antice non incisum ; tubercula ventralia duo pone cingulum sita ; 

 setae radiatim et seriatim positae, anteriores posterioribus numero- 

 siores, laeves, fusiformes, apice parum curvato. 



Several of the species referred to these six genera have been subsequently examined 

 by Pereier and by myself; they proved to be 'merely variations on the theme of 

 Perichaeta.' It is hardly necessary at the present time to insist upon the worthlessness 

 of the above characters as serving to discriminate genera. And yet Va-illant (6, p. 6^) 

 admits them as subgenera, iacluding Peeeier's genus Perionyx and a new subgenus 



