192 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



margins and converging toward the postero-dorsal median margin, 

 not shown in the figure. In some specimens the margins of the ven- 

 tral incision are thickened and extend backwards as a sort of lip, as 

 far as the V-shaped row of hooks, which are themselves sometimes 

 carried on an elevation continuous with this lip. This structure 

 does not show in all individuals and may be due to the preservation. 

 On either side of the operculum is a row of paleae, about 18 on a 

 side. The rows overlap ventrally but are separated dorsally by a 

 considerable gap. (Fig. 18.) In this gap is a pair of very heavy 

 hooks. Two rows of dark spines, grouped to form an inverted 

 V lie on the dorsal surface of the operculum. There may be some 

 variation in the number of these in each row ; 3 or 4 were found 

 in each of the individuals in this collection. A single row of flattened 

 cirri, approximately equal in number to the paleae and about as 

 long as these are, is attached to the margin of the operculum at the 

 bases of the paleae. Dorsally they are continued, for three or four 

 on a side, along a ridge which runs a little posterior to the level 

 of the large hooks. 



In preserved material, the two margins of the opercular stalks on 

 their ventral faces, are almost in contact, inclosing the tentacles 

 inside the groove thus formed. A single row of tentacles runs along 

 each margin. So far as can be told from the preserved material, 

 the tentacles have a length about equal to the diameter of the body. 

 Two long palps arise just in front of the mouth. They have smooth 

 surfaces, are circular in cross section, and taper to blunt points. In 

 the type they are heavy and extend to a distance of 5 mm. from the 

 surface of the body. In a much smaller specimen, they are very 

 slender and extend to a distance of 15 mm. Apparently they are 

 contractile and can be drawn into the ventral groove. 



The first somite behind the mouth has a row of gills on either side. 

 In the type, there are four of these on the left side, each shaped 

 much like the opercular cirri and not much larger than they, and 

 only two on the right side, one of these, however, being more than 

 twice as broad as any of the others. The four following somites 

 have each a small ventral seta tuft and a dorsal elevated torus carry- 

 ing a row of heavy spines. The first of these tori is much the 

 smallest. Behind this region each somite has smaller but very 

 prominent tori and gills. The latter are too poorly preserved for 

 accurate description, but are relatively long and narrow, tapering 

 to an acute point and are pigmented. On the torus is a row of 

 pectinate uncini. 



The opercular paleae are light straw in color and apparently have 

 rounded tips, though they were all badly broken in the material I 

 had. The thoracic paleaelike setae have much the same form as 



