4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 75 



others is so badly preserved that it is available only for setae and jaw 

 study, while the third, very much smaller than the others, is in 

 excellent preservation. This last has a prostomial width of 2 mm. 

 and the first 34 somites are 15 mm. long. Behind the 34th somite 

 the body is evidently undergoing regeneration for it is very] slender 

 and the appendages poorly developed. The drawing of the head and 

 parapodia are taken from this specimen, that of the jaw from a much 

 larger one. This should be remembered in considering the relative 

 sizes of the two. 



The prostomium (fig. 7) is bilobed, each half unusually rounded in 

 outline, the eyes dark brown in color and with obvious lenses. The 

 peristomium is about equal in length to the three following somites, 

 its anterior margin straight, the anterior lateral angles only slightly 

 rounded. The median tentacle extends as far as the anterior border 

 of somite 7 and is composed of 6 joints, of which the first is about as 

 long as the prostomium, the next a little shorter, the others shorter 

 still but of about equal length. The intersegmental furrows are much 

 more evident toward the distal end. The inner and outer paired 

 tentacles are essentially similar in form to the unpaired but are pro- 

 gressively shorter. Somite 2 is about one-fourth as long as somite 1 , 

 and its nuchal cirri are very long, slender, and jointed. Throughout 

 the body the dorsal cirri are rather stout, tapering in form, and two- 

 jointed. (Fig. 8.) 



In the small specimen the gills appear first as 2-branched organs 

 on the third setigerous somite, in the larger animal they arise from 

 this same somite and are 4-branched. In following somites the 

 number in the smaller specimen are, respectively, 4, 5, and 6. In the 

 larger they are 7, 8, and 9. In the latter animal there are 10 on 

 somite 13. Between somites 5 and 22, where the body is widest, the 

 gills are prominent and cover one-third of the dorsal surface of the 

 body on either side. Behind somite 22 the body narrows and the 

 gills become smaller and have fewer branches. They are present on 

 the last somite of the fragment where they have three branches. 



The tenth parapodium (fig. 8) has a setal lobe with a straight 

 anterior lip and a longer pointed posterior one, with two straight 

 aciculae coming to the surface between them. The ventral cirrus is 

 a triangular lobe on the end of a globular swelling, the dorsal cirrus 

 is stout and two-jointed. The main stem of the gill, which rises 

 near the base of the dorsal cirrus, is almost equal to the cirrus in 

 diameter and the diameter decreases very little up to beyond the 

 point of origin of the fourth gill-branch. There are six branches, the 

 tip of the last two having been broken in the one figured. Relatively 

 to the size of the parapodium the gill structure is heavy. Posterior 

 to about the twentieth somite the globular swelling which carries 

 the ventral cirrus disappears and a ventral hooked acicula comes to 

 the surface ventral to the setal lobe. All aciculae are black and 

 visible to the naked eye as dark spots on the parapodia. 



