86 THE ANNELIDA POLYCHAETA. 



Synonymy of Genera. 

 Acoetes Milne Edwards is the same as the older Polyodontes Renier, but 

 the latter name, being preoccupied, is not available. Eupompe Kinberg is also 

 synonymous with Acoetes. Euarche Ehlers is a synonym of Eupanthalis 

 Mcintosh. 



Panthalis Kinberg. 



Ofvers. K. vet. akad. Forh., 1865, no. 4, p. 386; McIntosh, British annelids, 1900, 1, pt. 2, p. 400. 

 Acoetes Darboux, Bull. sci. France & Belgique, 1900, 30, p. 117 (in part). 



Panthalis panamensis, sp. nov. 

 Plate 11, fig. 4-8; Plate 2, fig. 1-6. 



The posterior end of the type is missing. The part present has sixty somites 

 caudad of the peristomium. It is, exclusive of the protruded proboscis, 30 mm. 

 long with a maximum width, over all, of 6 mm. The maximum width is 

 about 6 mm. from the anterior end. From that level the body narrows cephalad 

 and more slightly caudad. 



The general color is a light brown with the parapodia yellowish; darker 

 anteriorly but with no distinct markings at present detectable. 



The prostomium is divided into two halves as usual; each half presents a 

 distally much enlarged ommatophore, the half as a whole being clavately thick- 

 ened proximad and distad from the narrow base of the ommatophore, but with 

 the proximal region, or prostomial lobe proper, considerably the larger. Ommat- 

 ophore and prostomium proper about equal in length. At its distal end each 

 ommatophore bears a conspicuous eye. It is darkened two thirds the distance 

 to its base. At the base of each ommatophore above there is a small but con- 

 spicuous, black, sessile eye. The median tentacle arises in the usual position 

 between the prostomial lobes; it narrows slightly distad to a level below the 

 apices of the ommatophores, where it narrows more abruptly to a slender tip 

 which extends distally beyond the ommatophores. The lateral tentacles are 

 similar in form and length. Each has a pigmented area proximally. The 

 palpi are long and acuminate, in the present contracted condition in the type 

 being two and a half to three times as long as the prostomium and ommato- 

 phores. 



The ceratophores of the cirri of the peristomial parapodia are distally on a 



