Structure of the Mouth in Sucking Crustacea. 259 



Anthura the palpus of the maxilliped has only two joints, and 

 the stipes lacks the rudimentary lobe. The first and second 

 pair of maxillae are essentially of similar build ; but in Anthura 

 the latter are joined together in their whole length, and cover 

 only the apices of the first pair of maxillae. The lobes of 

 the tongue are without the little digitiform prolongation which 

 in y^ga twists itself round the mandibular lobes. The stipes 

 of the mandible is much shorter in Anthura; it is supplied with 

 an articular protuberance ; but its outer margin is overlapped 

 by the margin of the pleura ; the inner lobe is present and 

 developed into a saw-blade ; the terminal joint of the palpus 

 is much longer than in JEga^ and differently constructed. 



As regards the totality of the oral organs and their mode 

 of cooperation, Anthura differs from Cymothoidse by the less 

 elaborate equipment of the aperture of the sucking-tube ; the 

 upper lip has no fringes ; and instead of a close armature of 

 hooked warts the lobes of the second pair of maxillse have only 

 small conoid warts, and the palpi of the maxillipeds only carry 

 some setse. But the greatest difference is observable with re- 

 gard to the manner in which the nourishment is made to flow 

 into the oral tube, the scratching hooks of ^ga and the lan- 

 cet-blades of Cymothoa being in Anthura replaced by com- 

 pletely developed sawblades, viz. the inner lobes of the 

 mandibles ; when the apical teeth of the outer lobes have taken 

 hold, these sawblades will be able to cut off extremely small 

 particles, their movement against each other being regulated 

 by the inner corners of the outer lobes, which project like 

 teeth and prevent the inner lobes from crossing each other 

 beyond the cutting parts of the sawblades. 



The formula for Anthura will consequently be the fol- 

 lowing : — 



Anthura. 



Os haustellatum. 



Haustellum adversum clypeo labroque, aversum maxillis poste- 

 rioribus palpisque pedum maxillarium confectum, malas 

 mandibulares serratorias maxillaresque priores rasorias 

 involvens. 



Clypeus obconicus, pendulus. 



Labrum transversum, fornicatum, late emarginatum, pen- 

 dulum. 



Mandihulce stipite depresso, amplo, trapezoideo, fixo, apice pal-, 

 pigero, malis binis. Mala exterior sub labrum oblique 

 inflexa, mobilis, in orificium haustelli eminens, falcata, 

 basi dentata, apice obtuse serrata. Mala interior cum 

 mala priore concreta, laminata, acie arcuata, acute serru- 



