4 Messrs. T. and A. Scolt on some 



The rudimentary character of the mandible-palp, together 

 with ihe two-jointed outer branches of first pair of feet, sepa- 

 rate Maraenobiotus distinctly from any other genus of the 

 freshwater Harpacticidae. We have not been able to give a 

 figure of the mandible- palp, and therefore quote the following 

 reference to it from Herr Al. Mrazek's description. He 

 says : — " Als ein wichtlger Charakter muss hervorgehoben 

 werden, dass der Mandibularpalpus sehr riickgebildet ist, 

 namlich nur duich einen kleinen drei schwache Borsten 

 tragenden Hocker reprasentirt wird." 



Allheyella Duthiei^ sp. n. (PL II. figs. 1-13.) 



Description of the Species. — Female. Length "9 millim. 

 (sV <^f ail inch). Posterior margins of the second to the fifth 

 thoracic segments serrulated ; the abdominal segments have 

 a fringe of cilia posteriorly ; rostrum of moderate length 

 (fig. 1). Antennules short, eight-jointed; the first two joints 

 are more dilated than the others and the fifth and seventh are 

 somewhat shorter ; the approximate proportional lengths of 

 the joints are shown by the formula — 



Proportional lengths of the joints. . 16 . 16 . 13 . 12 . 10 ■ 13 . 9 . 13 

 Number of the joints 1 2 3 4 5 6 7 8 ' 



The antennules are moderately setiferous and bear a short 

 sensory filament at the upper angle of the fourth joint (fig. 2). 

 Antennse stout, two-jointed ; the secondary branch consists 

 of a single comparatively slender and elongate joint, which 

 is furnished with a few setae at the distal end (fig. 3). The 

 mandibles have the biting-part armed with two or three 

 Jamelliform plates slightly notched at the apex ; the mandible- 

 palp has the basal portion moderately stout, to which is 

 articulated near the distal end a single one-jointed setiferous 

 branch (fig. 4). Maxillse and first and second foot-jaws 

 somewhat similar to those of Canthocamptus liirticornis^ 

 T. Scott. The inner branches of the first pair of swimming- 

 feet, which scarcely reach beyond the end of the outer branches, 

 are composed of two joints of nearly equal length, but the 

 end-joint is much more slender than the other; the first joint 

 bears a short plumose seta near the distal end and the second 

 joint a similar seta near the middle of the inner margin, 

 while the inner and outer margins of both joints are more or 

 less fringed with cilia ; in the second joint the middle one of 

 the three terminal setjeis very long and slender, the inner one 

 is very short and plumose, while the outer is elongate, slender, 

 and somewhat claw-like ; the outer branches, which are com- 



