6 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 69 



Genus LEPIDONOTUS Leach 



LEPIDONOTUS SQUAMATUS Linnaeus 



Aphrodita squamata Linnaejus, 1766, p. 1084. 

 One small specimen collected at Pango Pango, Samoa. 



Genus THORMORA Baird 



THORMORA TRISSOCHAETA Grube 



Lepidanotus trissochaetus Grube, 1869, pp. 485, 486; 1878, pp. 25, 26, 

 pl. 2, fig. 4. 



Grube (1869) described this species from collections made by 

 Ehrenberg in the Red Sea, Later (1878) he wrote a furthur de- 

 scription with a few figures, from material collected in the Philip- 

 pines. It seems quite certain that this is identical with specimens 

 in my own collections, but I have added the following descriptions 

 and figures to what Grube has written. 



These specimens have two forms of setae in the notopodium, and 

 the elytra leave a portion of the mid-dorsal line of the body un- 

 covered, in both of which points they differ from the usual diagnosis 

 of Le2)ido7iotus, and agree with Baird's (1865, p. 199), diagnosis of 

 a new genus Thonnora. I have, accordingly listed them under this 

 genus. It should be noted that the double nature of the notopodial 

 setae is not always clearly seen. The smaller, smooth margined 

 setae are quite obvious in some specimens, while in others it was 

 necessary to examine a number of parapodia before any were found. 

 I have no information as to wdiether there is any regular discon- 

 tinuity in their distribution along the animal, but think there is not, 

 and that this was an individual variation. To determine this point 

 would involve destroying a considerable number of specimens which 

 I did not have at my disposal. It would, however, be safe to suspect 

 that a Lepidonotus-like Polynoid with a bare dorsal surface has two 

 kinds of dorsal setae. 



The prostomium (fig. 4), is small, not more than 0.6 mm. in 

 width, its width being slightly greater than its length. The dorsal 

 surface is without pigment but is faintly iridescent. Its posterior 

 border is covered by a nuchal fold from the anterior border of the 

 first somite. The posterior eyes are near the border and are ob- 

 scured by the nuchal fold, while the anterior eyes are situated at 

 the widest part of the prostomium and are larger than the pos- 

 terior. On the dorsal surface of the prostomium is a distinct de- 

 pression, widest at the anterior border of the prostomium and run- 

 ning posteriorly nearly to the middle of the latter. The ceratophore 

 of the median tentacle fits into this depression. The lateral ten- 

 tacular ceratophores are slender, about half as long as the pro- 

 stomium, and are dark gray in tone, with the margin of the apex 



