86 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 7 



The elytra are smooth, translucent along the lateral margins. Sub- 

 marginally there is a diffuse pigmented crescent, open anteriorly. There 

 are no elytral spines or prickles, but the lateral margins are curved up- 

 ward and have a depressed pouch external to the elytral scar (pi. 25, 

 fig. 304). 



No papillar or lobular branchial structures could be discerned on 

 the first 37 segments. The presence of pointed superior neuropodial 

 setae and the absence of penicillate setae indicate its allocation to the 

 genus Polyodontes as restricted above. 



Polyodontes frons approaches Polyodontes adumbrata (Hoagland) 

 (1920, p. 606) from the Philippine Islands. It has greatly elongate 

 ommatophores and similar parapodial parts. P. adumbrata, however, was 

 said to lack capillary notopodial setae, and the elytra do not have lateral 

 pouches such as characterize P. frons. P. maxillosus Ranzani (see 

 Fauvel, 1923, p. 97) has elongate ommatophores and elytra with lateral 

 pouches, but the prostomium is proportionately much shorter and lacks 

 the median ridge; also, there are branchial lobes from about the thir- 

 teenth segment. 



Distribution. — Pinas Bay, Panama. In 20 fms. 



Genus PANTHALIS Kinberg, char, emend. 



Like Polyodontes Renier, but differs in that the neuropodial setae 

 consist of the following kinds : ( 1 ) superior penicillate setae with a 

 bushy top, the penicillae in some limited almost entirely to the tip, in 

 others carried somewhat subdistally, (2) median stout aristate setae, 

 and (3) inferior, sickle-like, serrulate setae. Some anterior parapodia 

 usually have slender capillary setae. Branchiae, in the form of digitate 

 parapodial lobulae, are absent or present. 



The following species that have been described may be considered 

 to be Panthalis as thus defined. 



1. Panthalis bicolor Grube (1878b, p. 157) from Congo, Africa (see 

 Augener, 1918, pp. 119-125). Monro (1928a, p. 572) considers 

 this a likely synonym of P. melanonotus Grube. 



2. Eupanthalis evanida Treadwell (1926, p. 186) from the Philip- 

 pine Islands (see Hartman, 1938, p. 127). 



3. Panthalis gracilis Kinberg (1910, p. 26) from Rio de Janeiro, 

 Brazil. 



