336 PEECT SLADEN TllUST EXPEDITlOISr. 



Genus POLYNOE. 



12. Folyno'e platycirrus, Mcintosh. (Plate 18. fig. 8; Plate 20. fig. 28.) 

 Mcintosh, Polycbseta, ' Challenger' Reports, xii. pp. 111-114, pi. 3. fig. 4, &o. (Australia). 



Measurements. One specimen, from Minikoi, was 33 mm. long, 6 mm. broad (with 

 setas), had 47 segments and 22 pairs of elytra. The other example, from Diego Garcia, 

 was 30 mm. long and had 19 pairs of elytra. 



The head is distinctly hexagonal in form. Mcintosh has called attention to the 

 JLepido>wius-like character, owing to the production of the anterior portions into the 

 lateral and median tentacles. 



The elytra are found on segments 2, 4, 5, 7, and on alternate segments till quite 

 the end, only the last five segments remaining unprovided. The whole of the back 

 is covered. In both specimens the striped ajipearance so characteristic of the type 

 specimen is shown ; it is due to vertical bands of brown pigment nearly continuous 

 from elytron to elytron. In the example from Minikoi the concentration of the brown 

 pigment in bands is only found in the anterior elytra ; jiosteriorly the elyti'a are more 

 uniformly pigmented. The striking peculiarity of this worm is the presence of two 

 well-marked keels on each elytron (fig. 8) running parallel to the outer margin in the 

 posterior half. No trace of these structures is found in the Diego Garcia example, 

 though otherwise almost complete similarity exists. The irregular ovate character of 

 the elytra is peculiar, with the broadest end pointing anteriorly and outwards. 



The notopodium (see fig. 28) is represented throughout only by a tubercle, penetrated 

 by the aciculum, but never containing any setae. This is perhaps the most marked 

 diff'erence from the ' Challenger ' type, which possessed a few notopodial setae. The 

 neuropodium carries numerous rather slender setts in a compact tuft. These, well 

 figured by Mcintosh (pi. viii. a, fig. 14), have a hooked apex, with sharp spur underneath 

 and short spiuiferous area markedly broader than shaft of seta. 



The flattened dorsal cirri which give their name to the species are characteristically 

 developed in the Indian Ocean forms. They extend as far as the end of the ventral 

 setae. 



In the worm from Diego Garcia the body is light yellow and the elytra are reddish 

 brown, the striping being very marked ; tliat from Minikoi has a dark brown body and 

 the elytra are light brown with a white spot over the elylrophore, developed to a slighter 

 extent in the first-mentioned form. 



LocalUies. Minikoi. Diego Garcia. 



13. Folynoii longicirrus, sp. n. (Plate 18. fig. 9; Plate 20. fig. 29; Plate 21. figs. 37, 38.) 

 Measurements. Length varies from 65 mm. to 75 mm., breadth with elytra 2 mm. ; 

 no. of segments 38. 



Minute form with flattened body. Head (fig. 9) distinctly divided into two oval 

 divisions by a median groove, and with no indications of eyes. Median tentacle long, 

 about four times length of j^alps ; lateral tentacles half the length of median. Elytra 

 very large, not only meeting over dorsum but projecting far beyond parapodia, colourless, 



