§ 306. THE ARACHNOIDAE. 377 



small animals can pierce or cut as may be required. These cheliceres are 

 free, or lodged in a sheath out of which they may be protruded ; some- 

 times they are covered, above or below, by a frontal or chin-like process. 

 In a few instances, these processes are united, forming a proboscis out of 

 which the cheliceres may be protruded.*-^ The first pair of maxillae, 

 which are inserted on the sides of the cheliceres, are wholly unfit for masti- 

 catory organs, and, being destined for tactile parts, they have the form of 

 palpi. These palpi are sometimes multi-articulated, sometimes uni-articu- 

 lated, and, from their various modifications, have received the names of 

 Palpi rapaces, anchorarii, fusiformes, filiformes, antenniformes, valvae- 

 formes, and adnatiS^^ 



3. The Oribatea, which, from their herbivorous nature, hold a distinct 

 place, not only among the Acarina, but also among the Arachnoidae in gen- 

 eral, are distinguished also for the organization of their buccal organs. 

 Their cheliceres are protractile, and the first pair of maxillae, situated 

 under them, forms a complete masticatory apparatus, their basilar article 

 being developed at the expense of the rest into a large denticulated 

 piece. The other articles form only a very short palpus.**' 



4. The Pycuogonidae, Opilionina, Pseudoscorpii, Galeodea, and Scor- 

 pionidae, all, have tri-articulated cheliceres. Under these last are situated 

 the first pair of maxillae which have no masticatory character.*^' With 

 the Scorpionidae, and Pseudoscorpii, they are long-forficulate, while, with 

 the Galeodea, the Pycuogonidae and Opilionina, they are antenniform. 

 With the Phalangidae, only, there is observed on their basilar article, a 

 hairy, obtuse appendage, comparable to a rudimentary maxilla.''^' With 

 the Scorpionidae, the two basilar articles of the pincers are so approx- 

 imated by their flattened internal surfaces, that they may well be used for 

 the bruising of soft animal substances.''* 



5. With the Phrynidae, and Aranoae, the cheliceres have the form of 

 bi-artlculated, unciform antennae. The basilar article of these so-called 

 mandibles is always very thick, and the terminal article consists of a 

 small, very sharp hook.''*' When at rest, this last lies folded on the inter- 



2 For the cheliceres of the Acarina, see the de- 4 I have satisfied myself of the presence of 

 scriptions and figures of Hermann^ Dugis, and horny denticulated maxillae, fitted for mastication, 

 Dujardin,i\oc. c\l.). These organs are forficulate v/ith Hoplophora^ Pelops, Zetes, Oribates, Da- 

 with the Acarea, Gamasea and Bdellea ; see Du- maeus, and with other Oribatea. 



jardin, Observ. au Microsc. PI. XVII. fig. 10, 11 5 Some Pycuogonidae form the only exception in 



(^Acarus). They are uuguiculate with Tromhidi- this respect. With Pariboea, the cheliceres are 



um, Erythraeiis, Smaridia, Atax, and Eyla'is ; simple, bi-articulate and olavate ; but with £jideis, 



see Treviraiius, Verm. Schrift. I.Taf. V. tig. 29 Pycnogonum, and P/ioxic hi lus, they are wholly 



{Trombidium). They are styliform with the Ix- wauting ; see Philippi, in fFiegmanri's Arch. 



odes, Tetranychus, Rhyncholophus, Rhaphig- 1843, I. Taf. IX. fig. 1-3 ; also Savii^ny, Johns- 



nathus, and Hydrachna. The frontal proUmga- ton, and Milne Edwards, loc. cit. 



tion is regarded by some authors as an under lip. 6 Savigny, Mem. &;o. I. PI. VI. fig. 2, d. 



It is found with Dermanyssus and Rliapiiiiina- 'i It is well known that the Scorpionidae and 



thus ; while, with Ixodes, it belongs to the chin, the other rapacious Arachnoidae, merely suck 



and thus forms an under lip. With Smaridia, their prey ; but it is said that Galeodes devours 



and Sarcoptes, the cheliceres are encompassed \>y completely the insects which it has caught, seizing 



a kind of tube ; see Dujardin (Observat. &c. PI. them with their cheliceres, and eating them piece 



XVII. fig. 1-4 (Sarcoptes). With Ixodes, the by piece. During these processes each chelicere 



cheliceres are cultrate and denticulate on their acts separately (Hutton, Ann. of Nat. Hist. XII. 



external borders ; see Savigny, Descript. de 1843, p. 81, or Froriep^s neue Not. XXVIII. p. 



I'Egypte, PI. IX. and Audouin, Ann. d. Sc. Nat. 49). The Phalangidae have probably the same 



XXV. PI. XIV. The brevity and inequality of Iiabits, for fragments of insects which they have 



these organs, as noticed by ^Mtiouui vfith Ixodes eaten are found in their digestive canal (Tulk, 



erinacei, were due to the ch'cumstance that they loc. cit. p. 248). 



were imperfectly and unequally protruded from ^ See Roesel, loc. cit. Taf. XXXVII., and Sa- 



their sheath. vigny, Descript. de I'Egypte, PI. I.-VIII., also Ly- 



3 This classification of the palpi belongs to Du- onet, loc. cit. PI. XIX. XXI. 

 gis ; see Ann. d. Sc. Nat. I. p. 11. 



32* 



