84: Till: FOLLOWERS OF GKOFFROY 



second with the anterior appendages of Articulates gener- 

 ally. Savigny shows that the mouth-parts of insects can 

 be reduced to the type shown in Orthoptera, where there 

 are clearly two mandibles, two maxillae, and a lower lip 

 formed by the fusion of two second maxillae. All other 

 insects have these same mouth-parts, disposed in the same 

 . order, however much their form may have been modified in 

 response to new functions. He goes on to compare the 

 anterior set of appendages in a long series of Articulates, in 

 fnlns, Scolopcndra, Caticcr, Gam-morns > Cyamus, XyinpJwn, 

 Phalangium^ Apns> Caligits, Limit Ins, and a few others. For 

 Crustacea he established the homologies now accepted, of the 

 mandibles with the mandibles of insects, of the first and 

 second pairs of maxillae with the parts so named in insects, 

 and so on. He is quite clear that the maxillipedes of" 

 Crustacea are the homologues of the feet of Hexapoda. 

 " Their disposition must lead one to think that the six 

 anterior feet of Jnlus, that is to say, all the feet of the 

 Hexapoda, are here transformed into jaws " (loc. cit., p. 4,S). 

 In Scolopatdm also there is a similar transformation of two 

 pairs of legs into auxiliary jaws. In Gaiiniianis, where there 

 is only the first pair of maxillipedes, the other two pairs 

 have become " retransformed " into feet. \Ve find him 

 supporting his comparison of the three anterior pairs of legs 

 \\-\ Jnlns to the three pairs of legs in insects by an argument 

 drawn from embryology ; for only the first three pairs of feet 

 are present in Jnlns at birth (Degeer), " an observation, 

 which, together with their position, should cause them 

 to be considered as the representatives of the six thoracic 

 feet of Hexapoda" (p. 44). 



1 1 is comparison of the Arachnid appendages with those 

 of insects and Crustacea is very curious. As his starting- 

 point he takes Cydi/ms, which has antenn;e (two pairs) and 

 mouth parts (four pairs) as in many Crustacea, and then 

 seven pairs of legs ; he compares with it Xyniplion, which has 

 in all seven pairs of appendages. These appendages he 

 homologises with the seven pairs of legs of Cyainns, so that 

 the first appendage in Xymplioii corresponds to the seventh 

 appendage of Cy^tnns. This homology is extended to 

 all Arachnids ; their first two pairs of appendages, however 



