132 G. O. SARS. CRUSTACEA. [NORW. POL. EXP. 



joint is very small and is movably articulated to the 1st, admitting, by the 

 aid of 2 distinct muscles joining it, of being extended in front or reflexed. 

 It carries on the tip 5 setiform appendages, the middle one being twice as 

 long as the others, which are sensory in character. 



The oral orifice (see PL XXXVI, figs. 1 & 2) is bounded by 2 well- 

 defined lips, the anterior of which is very large, forming in front a very 

 prominent, hood-like expansion, which is visible immediately below the basal 

 part of the antennae (see PI. XXXV, fig. 1). The posterior edge, bounding 

 the oral orifice in front, is highly chitinized and somewhat produced in 

 the middle, exhibiting, on each side, a closely striated lamellar border. The 

 posterior lip projects in 2 movable, incurved lappets of a somewhat securi- 

 form shape, and finely ciliated at the edges. Immediately behind this lip, 

 the so-called sternal plate occurs, and from it several chitinous fillets originate, 

 extending in different directions, to strengthen the insertions of the post-oral 

 appendages. 



The mandibles (PI. XXXV, fig. 6), unlike what is generally the case in 

 this division of Ostracoda, exhibit each a well-defined and highly chitinized 

 body of narrow cuneiform shape, extending obliquely anteriorly across 

 the sides of the cephalic part, immediately behind the basal part of the 

 antennae (see fig. 1). The masticatory part is defined by a neck-shaped con- 

 striction, and is squeezed in between the anterior and posterior lips. It is 

 highly chitinized, and of a brownish hue, projecting in front to a short 

 dentiform prominence. The cutting edge is divided into several short teeth, 

 and immediately inside it is a closely fluted and hairy triturating surface, 

 representing the molar tubercle (see fig. 7). The palp is very large and 

 pronouncedly pediform, extending in front, on each side of the anterior lip, 

 with the distal part curved downwards. It is composed of 4 well-defined 

 joints, the 1st of which is much the largest, about the length of the 2 suc- 

 ceeding ones combined, and considerably dilated in its proximal part. This 

 joint forms a rather large expansion below, with several slender setae on 

 the outer face, and extending as far as the tip of the masticatory part, out- 

 side which it lies. The narrowly truncated end of this expansion is divided 

 into a row of short teeth, which no doubt assist the mandibles in cutting 

 the food asunder. From the upper edge of this joint, at some distance 



