160 ARACHNIDES. 



the Arachnides, where the mouth has the form of a siphon or 

 sucker, by two pointed blades which act as lancets(l). A 

 kind of lip — labium, Fab. — or rather ligula, produced by a 

 pectoral prolongation; two jaws formed by the radical joint of 

 the first segment of two small legs or palpi (2), or by an ap- 

 pendage or lobe of that same joint ; a part concealed under 

 the mandibles, called langue sternale by Savigny — descrip- 

 tion and figure of the Phalangium copticum — and composed 

 of a projection in the form of a rostrum, produced by the union 

 of a very small clypeus terminated by an extremely small tri- 

 angular labrum, and of an inferior longitudinal carina, usually 

 very hairy, are the parts, which, with the pieces termed 

 mandibles, constitute with some modifications the mouth of 

 most of the Arachnides. The pharynx(3) is placed before a 

 sternal projection which has been considered as a lip, but 

 which, from being placed directly behind the pharynx and 

 having no palpi, is rather a ligula. The legs, like those of 



(1) Chelicerx, or forceps-aniennx: the evident result of the comparison between 

 them and the intermediate antennae of various Crustacea, those of the PBCcilopoda 

 particularly. It cannot then be said, strictly speaking, that the Arachnides are 

 deprived of antennae, a negative character, which, previous to us, had been ex- 

 clusively attributed to them. 



(2) They only differ from legs properly so called, by their tarsi, which are 

 composed of a single joint, and are usually terminated by a small hook, resem- 

 bling, in a word, the ordinary feet of the Crustacea. See our general observa- 

 tions on the first order. These jaws and palpi appear to correspond to the pal- 

 pigerous mandibles of the Decapoda and to the two anterior feet of tlie Limuli. 

 In Phalangium, the four following legs have a maxillary appendage at their origin, 

 so that these four appendages are analogous to the four jaws of the preceding 

 animals. I had described these parts, long before the publication of Savigny's 

 memoirs on the invertebrate animals, in a monograph of the species of this 

 genus proper to France. From these and the preceding observations it is evi- 

 dent that tlie composition of these animals is easily reduced to the same general 

 type which characterizes all articulated animals with articulated feet. The Arach- 

 nides are not then a sort of acephalous Crustacea, as stated by this savant, usually 

 so exact in his anatomical observations, of which, unfortunately for the sciences, 

 he has become the victim. 



(3) Although Savigny admits of two orifices, neither Straus nor myself can find 

 but one; it must have been the eff'ect of an optical illusion, arising from the fact 

 of his having only perceived the lateral extremities of the fissure, its middle being 

 concealed by the tongue with which its anterior fiice is thickened in its mediate 

 portion. 



