I 



Structure of the Mouth in Sucking Crustacea. 255 



harmonious cooperation of all the j)art.s of the complicated 

 machinery to one end, and,tinally,to ajjprcciate the fundamental 

 types which may be discerned in the conformation of the 

 mouth in these Crustaceans. These questions can be solved 

 only by a well planned, ^^radually progressing dissection under 

 the microscope, carried out in such wise that the natural ])osi- 

 tion of each partis observed with certainty — a process difhcult 

 in itself, and involving the sacrifice of much time and many 

 specimens. As I shall have no other convenient opportunity 

 in the sequel for doing so, I shall here at once briefly indicate 

 how I interj)ret the figures which the authors quoted have 

 inserted in their ])agc 1G5 (vol. ii.) as representing the ])arts 

 of the mouth in Paranthura Costana, but which are not eluci- 

 dated either by references in the text or by any special expla- 

 nation. 



There are two figures marked f, of which the one to the 

 right no doubt represents one of the maxillipeds with its two- 

 jointed palpus, its stipes and cardo, together with the proslcr- 

 num, though the relative propoi-tion of these parts is not 

 accurately rendered (an observation which niay be made with 

 regard to several figures in this veiy useful work, but which 

 is accounted for by the consideration that the drawings evi- 

 dently are mere sketches intended to assist the student in 

 finding the parts). The other figure /" represents, as I believe, 

 the terminal portion of the same organ. The letter e denotes 

 one of the maxillce of th^ first pair (our authors seem to de- 

 scribe this pair as the second) ; fig. d is no doubt a mandible. 

 The left-hand figure of the two marked with a cross I take to 

 be drawn from a preparation including portions of the first and 

 second pairs of maxillaj in superposition ; whilst the other 

 figure with the same mark undoubtedly represents the upj^er 

 lip with the clypeus, confounded by pressure into one mass*. 



* In passing I may mention that the information given by Messrs. 

 Spence Rate and Westwood on Cunilera ct/littdracca proves unmistaJiably 

 that its mouth is formed for biting, and entirely agi-ees with that of 

 Cirohini, whilst diflering widely from that of ylu/ci, which, as I have 

 shown in the funner part of this treatise, is fonned for suction. If, 

 therefore, we are to be guided in our systematic an-angements by the 

 structure of the luouth, and not merely by the general external resem- 

 blance (habitus), Cirohini, and with them C'c»/»7<'rrt, must not be claa«ed 

 witli ^"Efio, but removed to the opposite extremity of the series of Iso- 

 poda. Having proved myself that .lu/n and Cijmothon are really sucking 

 Crustacea, I quite agree with om* authors when they plpce Anlhura next 

 to them on account of the structure of its mouth ; but this argument for 

 their classitication seems hardly consistent with their own statement 

 (vol. ii. p. -"-'i), that in " the second subtribe of the parasitical normal 

 group of the Isopoda f coiuprising Serolid.T>, .Egidop, and < 'ynmth'Mda"! 

 the oral organs are foini'd t'nr mastication." 



