tJie Mouth in Sucking Crustacea. 19 



yE(/a. 



Os liaustellatura. 



Haustellum adversum clypeo labroque, aversum malis poste- 

 rioribus palpisque pedum maxillarium confectum, malas 

 mandibulares maxillaresque priores rasorias involvens. 



Clypeus fornicatus pendiilus. 



Labrum semicirculatum, pendulum, fornicatum, margine 

 membranaceo, fimbriate verruculoso. 



Mandibulce stipite amplo, falcato, basi palpigero, mala inte- 

 riore nulla. Mala exterior sub labrum oblique inflexa, 

 mobilis, in oriiicium liaustelli deorsum eminens, triquetra, 

 acuminata, intra concaviuscula, apice extreme hamato, 

 acuto. Paljnis gracilis, triarticulatus, articulo intermedio 

 producto, terminali brevi, falcato, barbato, pectinato, 

 basin antennae secundse amplectente. 



Maxilloi pi-iores stiliformes, mala interiore et jyaljpo nullis. 

 Mala exterior stipiti contigua, in orificium liaustelli deor- 

 sum eminens, fasciculo armata terminali hamorum raso- 

 riorum. 



Maxillce posteriores apice contigua^, maxillas priores obvol- 

 ventes, stipite lato, fornicato, palpo nullo. Maloi dis- 

 cretge, breves, rotundata^, margine minute hamulata^, ori- 

 ficium liaustelli post claudentes, supra marginem inte- 

 riorem palporum pedum maxillarium reflexge. 



Pedes maxillares maxillas includentes, cardine maximo, obli- 

 que, laminato, triangulo, mala minutissima, conica. Sti- 

 pites contigui, recti, subquadrati, fornicati, supra carinati, 

 liypostoma valde elongatum medio carinatum utrinque 

 explentes, Palpyi quinquearticulati, latissinii, foliacei, 

 fornicati, infra minute hamulati, labia lateralia liaustelli 

 formantes. 



Lingua rotundata, mollis, pulvinata, nuda, fissa lobis apice 

 lingulatis, introrsum arete contiguis, crasse marginatis, 

 rimam suctoriam includentibus. 



13. Having now described the structure of the mouth in 

 ^ga as minutely as seemed necessary in order to explain its 

 composition and mode of action, we may, in respect of Cymo- 

 tlioa (fig. 6), content ourselves with a comparison between the 

 two, pointing out and interpreting the differences. 



The oral tube is built up of the same elements ; but they 

 enter into its composition in different proportions ; and an im- 

 portant difference in this respect is to be noticed between the 

 two sexes. 



In the male the cardo of the maxillipeds is a large, trans- 

 versely oval but very irregular plate. The stem is flat, ob- 



2* 



