40 G. 0. SARS. CRUSTACEA. [norw. pol. exp. 



at the tip, and carrying about 14 long seta; arranged in a flabelliform manner. 

 The outer ramus, which is very mobile, is somewhat shorter than the inner, 

 and is cylindric in form. It is composed of 6 joints, the 2nd and last of which 

 are the largest, the 3 joints lying between them being very short. This ramus 

 carries 3 exceedingly long and finely plumose apical setae, and 4 lateral ones 

 of the same structure, the outermost of which, however, is rather short. 



The oral aperture (see PL VII, fig. 3) is bounded in front by a rather 

 voluminous, flap-shaped anterior hp, and behind by a much smaller bilobular 

 posterior lip, both being to some extent finely ciliated on the edges turned 

 towards the mouth. 



The mandibles (see PI. VIII, figs. 3, 4) have the masticatory part rather 

 produced, but only slightly expanded distally, with the cutting teeth densely 

 crowded together, and bidentate at the tip, the outer one not, as is usually 

 the case, differing from the others. The palp is very fully developed, being 

 rather larger than the body of the mandible, and, hke the posterior antennae, 

 is composed of a biarticulate basal part, and 3 unequal rami. The 1st basal 

 joint is very small and easily overlooked, whereas the 2nd is large and broad, 

 slightly widening distally, and provided inside with a single small bristle. The 

 inner ramus is very short and composed of 2 joints of about equal size, the 

 last carrying at the tip about 8 slender setae spread in a fan-like manner. 

 The outer ramus is very greatly developed, being more than twice as long 

 as the inner, and rather thick, fusiform in shape. It is divided into 5 well 

 defined joints, the last of which, however, is so very small, as easily to escape 

 attention. This ramus carries 6 extremely strong and elongated plumose 

 setae, 2 issuing from the last joint, and a single one fi-om each of the pre- 

 ceding joints. The setae gradually increase in length proximally, that issuing 

 from the 1st joint being from 8 to 10 times as long as the ramus itself. 



The maxillae (fig. 5) have the masticatory lobe narrowly produced, and 

 clothed with unusually slender spines. The opposite vibratory plate carries 

 8 plumose setae, the outermost of which is shorter than the others. The 

 remaining part of the maxilla is very delicate, membranous, and divided into 

 4 setiferous lobes, the 2 terminal ones more properly answering to the 2 

 rami in the posterior antenna and mandibular palp. Of these 2 lobes, only 

 the outer one is distinctly defined at the base, forming an oval, mobile lamella, 

 edged with 7 curved setae. 



