NO. 1 hartman: polychaetous annelids 81 



More complete studies of the species in these genera, based on entire 

 individuals, will perhaps disclose more obvious differences than have 

 been found thus far. The differences as now^ set forth do not clearly 

 warrant the retention of both generic names, though the separation is a 

 convenient one. Unfortunately, many of the species are known only in- 

 completely, often because of fragmentary materials. Many of the de- 

 scriptions are based on anterior ends. Hence, the portion which might 

 have had branchiae could not have been examined. Moreover, the pres- 

 ence or absence of branchial lobes, which has been used as a diagnostic 

 character in separating these two genera, is sometimes subject to acci- 

 dents and changes due to fixing and preservation. Because of these diffi- 

 culties, the presence or absence of branchial structures has herein been 

 ignored in separating the 2 genera, and the presence or absence of true 

 penicillate setae is used. 



The only setae that have been found to differ sufficiently to make 

 them of diagnostic value are the superior neuropodial setae, in the seg- 

 ments posterior to the first 2 to 5 segments. These setae are either peni- 

 cillate (with a bushy top), or elongate hastate, with smooth tip and 

 sides, or somewhat hirsute. The penicillate setae sometimes have the 

 tuft of hairs continued more or less down one side, their tips drawn out 

 in a point (P. melanonotus Grube). The hastate setae may have the hir- 

 sute condition continued to the tip (as in P. panamensis Chamberlin). 

 A transition from the penicillate seta to the hastate seta is thus demon- 

 strable. Most of the species that have been described thus far, however, 

 are not intermediate in this respect, but have setae either of the peni- 

 cillate type or the hastate type. Though artificial, this means of separa- 

 tion is convenient for most species concerned. 



The following definitions and classification for these 2 genera are 

 therefore proposed. 



Key to the Genera, Polyodontes Renier and Panthalis Kinberg 

 Superior neuropodial setae are elongate hastate, the tip smooth or 



more or less hirsute POLYODONTES 



Superior neuropodial setae are penicillate .... PANTHALIS 



Genus POLYODONTES Renier, char, emend. 



Prostomium with 3 antennae, a pair of anteriorly directed ommato- 

 phores each bearing a conspicuous lenticular eye, and usually a pair of 

 sessile eyes on the prostomium proper. Neuropodia provided with (1) 



