CRUSTACEA OF KEW ZEALAJSD. 213 



Schiodte's paper on the mouth-parts of Cyathura carinata referred to by Norman and 

 Stebbing *. I have consulted Dohrn's paper on Paranthura costana [36] with much 

 benefit. Cruregens, however, difi'ers from all other Anthuridae that I know in haviug 

 the mandibles entirely without palps, and the mouth-parts seem more specialized than 

 in other species. 



The projecting tube formed by the mouth-parts is closed above by the upper Up 

 (fig. 6), which projects downward and forward from lielow the bases of the lower 

 antennae. It consists of a triangular plate with doubly-curving sides and an acute 

 extremity, which is chitinous throughout and seems very hard and strong. The sides 

 of the tubes are enclosed by the greatly modified mandibles (fig. 7) and by the distal 

 portions of the much simplified maxillipedes, which also form the covering for the tube 

 below. The mandibles, which show no sign whatever of a palp, appear more or less 

 completely ankylosed to the wall of the head and almost incapable of independent 

 movement. Fig. 8 is a view of them from below and partly from the side, to show 

 how they are attached to the ends of the maxillipedes and form the covering on the sides 

 between them and the upper lip. The mandibles are subtriangular, running out to a 

 sharp point distally ; the distal portion bears on the inside a thin chitinous plate with 

 rounded margin, which is very thin and sharp, and perhaps acts as a lancet or cutting- 

 organ of some kind. 



Within the tube of the mouth, enclosed as above described, we should expect to find a 

 lower lip and two pairs of maxillae. Fig. 12 represents what I suppose to be the 

 lower lip ; it consists of an oblong plate narrowed at the base, with the distal extremity 

 truncate, the corners being rounded off and the extremity fringed with a few fine setae 

 directed forward. The margins appear to be curled in or thickened, and the centre is 

 strengthened by a thickening which extends distally from the narrow base and gradually 

 thins out. The jirst mawillce (figs. 9, 10) are easily recognized and are of the form 

 usual in this section of the Anthuridae ; they are very long, extending back at the base 

 nearly to the posterior end of the head ; each consists of a long, slightly curving, and 

 gradually tapering shaft, which bears at the extremity on the outside a fine saw-hke 

 edge made up of a number of sharp teeth ; on the opposite side is a thin flange curving 

 out from the maxilla and having a very sharp razor-like edge. The maxilla is acutely 

 pointed at the extremity : at the base it is jointed on to a short chitinous piece, which is 

 again jointed on to a curving transverse bar ; to the distal end of the first piece is attached 

 the tendon of a strong muscle, by the contraction of which the maxilla is protruded, while 

 it is drawn back again by muscles attached to the base of the maxilla itself ; possibly 

 also the maxilla can be somewhat rotated on its base so as to bring the two saw-like 

 edges together. In any case they evidently form most efficient lancet-like organs. It 

 appears probable from Dohrn's figure [36, pi. ix. fig. 8] that at the base of the first 

 maxilla of Paranthura costana there is an apparatus similar to that here described, but 

 his figure is not very clear and shows the transverse bar as though continuous with 

 the maxilla itself. 



• " Krebedyrencs Sugemund," Naturhistorisk Tidsskrift 3 R. 10 B. (1875), p. 211, tab. iv. 



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