20 G- O. Sars. 



divided into numerous short articulations, the greater part 

 of which are clothed anteriorly with dense transverse rows 

 of strong spiniform bristles. The rami are nearly twice as 

 long as the scape, and are each divided into about 9 

 somewhat lamellar articulations provided posteriorly with a 

 number of slender, densely ciliated natatory setæ, anteriorly 

 with short spines. The number of setæ and spines some- 

 what varies in the different articulations, being on the whole 

 greater on the distal than on the proximal articulations. 



The anterior lip (PI. II, figs. 5,6; PI. Ill, fig. 1) extends 

 posteriorly as an immediate continuation of the ventral sur- 

 face of the head, being only defined at the base by a very 

 slight depression. It has a convex lower face and a con- 

 cave upper one, and terminates in a very delicate tentacular 

 process, finely ciliated in its outer part. Seen from below 

 (PI. II, fig. 5), it appears rather broad in its proximal part, 

 exhibiting at the base of the terminal process on each side 

 a distinctly projecting corner. Between these corners issues 

 from the upper face (see fig. 6) an oval, vertical lamella, 

 which applies itself between the maxillæ, when the lip is 

 bent in against the oral area. Within the body of the lip 

 several glandular bodies may easily be traced, as also a 

 number of transverse muscular bands apparently acting 

 upon the soft upper part of the lip, and thus assisting in 

 the process of swallowing. 



The mandibles (see PL III, fig. 1) appear as a pair of 

 much bent bows extending on the sides of the head at its 

 junction with the cervical segment, and meeting below at 

 the oral aperture. On a closer examination (see PI. II, 

 fig. 7), the masticatory part is found to be defined from 

 the upper navicular part of the mandible by a distinct 



