On Steno cyp ris Chevreuxi. 15 



a very large semilunar branchial plate, which in the living 

 animal is seen to exhibit rhythmical vibratory movements. 

 The plate is provided along its outer edge with about 24 

 exceedingly strong and densely plumous setae, of which the 5 

 inferior ones are curved straight downwards. From the end of 

 the basal part issue 4 digitiform lobes, the most anterior 

 of which is much the largest, and is movably articulated to 

 the basal part. This lobe, which ought more properly to 

 be regarded as the palp, consists of 2 well-defined articula- 

 tions, the 1st of which is the larger, cylindric in form, and 

 provided at the end anteriorly with a number of slender 

 curved bristles. The distal joint (see fig. 7, a) is rather 

 short and very slightly expanded at the end, which is 

 obliquely truncated and armed with about 6 claw-like 

 bristles. The 3 other lobes, the true masticatory lobes, are 

 quite simple, diminishing successively in size, and each 

 carrying at the tip a bunch of strong, partly denticulated 

 spines. 



The posterior maxillæ (fig. 8) are much smaller than 

 the anterior, and of a rather différent structure. The basal 

 part is immediately continued as a simple masticatory lobe 

 extended obliquely forwards, and armed at the tip with a 

 dense bunch of slender spines, having also inside, at some 

 distance from the tip, some few similar spines. From the 

 posterior side of the basal part issues a conically tapering 

 lappet, which is extended straight backwards and terminates 

 in 3 setæ, of which the middle one is much longer than the 

 other 2. This lobe ought to be regarded as a peculiarly 

 modified palp. Immediately above it a small rounded branchial 

 plate is secured, carrying 6 densely plumous setæ. 



The anterior legs (fig. 9) are rather strongly built, and 

 consist each of a short and thick basal part and a more 



