14 G. O. Sars. 



so as to meet the one on the other side. Between the 2 

 chitiuous rods, a close striation is observed (see fig. 5), 

 and along the middle, a funnel-shaped depression occurs, 

 leading to the oesophagus. 



Immediately behind the posterior lip, the ventral face 

 of the body forms a somewhat prominent carinated plate, 

 lying between the insertions of the maxillæ. 



The mandibles (fig. 6) each consist of a strongly 

 chitinized body, and a well- developed pediform palp. The 

 body is of a somewhat cuneated shape, its upper part being 

 produced to an acute point, which is apparently articulated 

 to the inside of the shell. The dark horn-coloured masticatory 

 part is slightly incurved, and has exteriorly a small bristle. 

 The cutting edge is divided into 6 or 7 strong, dark brown 

 teeth, diminishing in size inwards, and coarsely denticulated 

 in their outer part, having between them stiff bristles. The 

 palp is about half the length of the mandible, and is curved 

 downwards. It consists of 4 well-defined joints, the 1st of 

 which is rather large, and carries at the end posteriorly 3 

 very strong and densely ciliated setæ. To the outer side 

 ■of this joint a comparatively small, recurved branchial 

 appendage is attached, carrying 6 densely plumous setæ, 4 

 of which issue from the transversely truncated tip, whereas 

 the 6th is secured to a separate ledge on the outer edge. 

 The 2nd joint of the palp is rather short, and carries both 

 anteriorly and posteriorly several slender bristles. The 3rd 

 joint is much larger, and is likewise provided on both 

 edges with a fascicle of bristles. Finally, the last joint is 

 very small and somewhat conically tapered, and carries on 

 the tip 3 or 4 short, spiniform bristles. 



The anterior maxillæ (fig. 7) each exhibit a thick and 

 muscular basal part, to the outer side of which is attached 



