Structure of the Mouth in Sucking Crustacea. 259 



Anthura tlie palpus of the inaxilliped has only two joints, and 

 the stipes laeks the ruclinieiitary lolx-. The first and second 

 ])air of niaxilhe are essentially of similar build ; hut in Anthura 

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

 only the a})iccs of the tirst pair (jf maxilhu. The lobes of 

 the tongue arc without the little digitifonn prolongation which 

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

 of the mandible is much shorter in Anthura', it is su[)plied with 

 an articular ])rotuberanee ; but its outer margin is overlapped 

 by the margin of the i)leura ; the iinier lobe is present and 

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

 is nnieh longer than in yl'^fjf^j and differently constructed. 



As regards the totality of the oral organs and their mode 

 of cooperation, Anthura diflers from Cymothoi(Ue by the less 

 elaborate equipment of the a])erture 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 maxillae have only 

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

 some seta?. But the greatest difterence is observable with re- 

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

 into the oral tube, the scratching hooks of yE(ja and the lan- 

 cet-blades of Cf/mothoa 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 Avill be able to cut off extremely small 

 ])articles, 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. 



HausteUmn adversum clypeo labroque, aversum maxillis poste- 

 rioribus nalpisquc pedum maxillarium eonfectum, malas 

 mandibulares serratorias maxillaresque priores rasorias 

 involvens. 



Clypeus obconicus, pendulus. 



Labruin transversum, fornicatum, late emarginatum, pen- 

 dulum. 



Mandibular stipite depresso, amplo, trapezoideo, fixo, apicc pal- 

 pigero, malis binis. Mala ccterior sub labrum oblique 

 innexa, raobilis, in orificium haustelli eminens, falcata, 

 basi dentata, apice obtuse senata. ^f(lIa interior cum 

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



