<^306. 



THE ARACHNOIDAE. 



B77 



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, JiUformes, antenniformes, valoae- 

 farmes, and adnati.^^^ 



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 Pycnogonidae, 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 Pycnogonidae 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-articulated, 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 Acariua, see the de- 

 scriptions and figures of Hermann, Dugis, and 

 Dujardin,{\oc. cit.). These orf^ans are forliculate 

 witli the Acarea, Gamasea and Bdellea ; see Du- 

 jardin, Observ. au Microsc. PI. XVII. fig. 10, 11 

 (Acai-ux). Thoy are unguiculate with Trombidi- 

 um, Erythraeus, Smaridia, Atax, and Eylais ; 

 see Treviranus, Verm. Schrift. I. Taf. V. fig. 29 

 (_Trombidium). They are styliforra with the Ix- 

 odes, Tetranychus, Rhyncholophus, Rhapkig- 

 nathu.i, and Hydrachna. The frontal prolonga- 

 tion is regarded by some authors as an under lip. 

 It is found with Dermanyssus and Rhapkigna- 

 thus ; while, with Ixodes, it belongs to the chin, 

 and thus forms an under lip. With Smaridia, 

 and Sarcoptes, the cheliceres are encompassed by 

 a kind of tube ; see Dujardin (Observat. &c. PI. 

 XVII. fig. 1-4 (Sarcoptes). With Ixodes, the 

 cheliceres are cultrate and denticulate on their 

 external borders ; see Savig'ny, Descript. de 

 PEgypte, PI. IX. and Audouin, Ann. d. Sc. Nat. 

 XXV. PI. XIV. The brevity and iuequaiity of 

 these organs, as noticed by Audouin with Ixodes 

 ermacej, were due to the circumstance that they 

 were imperfectly and unequally protruded from 

 their sheath. 



3 This classification of the palpi belongs to Du- 

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



32* 



4 I have satisfied myself of the presence of 

 horny denticulated maxillae, fitted for mastication, 

 with Hoplophora, Pelops, Zetes, Oribates, Da- 

 maeus, and with other Oril>atea. 



5 Some Pycnogonidae form the only exception in 

 this respect. With Pariboea, the cheliceres are 

 simple, bi-articulate and clavate ; but with Endets, 

 Pycnogonum, and Phoxichilus, they are wholly 

 wanting ; see Philippi, in ffie^mann's Arch. 

 1843, I. Taf. I.X. fig. 1-3 ; also Savii^ny, Johns- 

 ton, and Milne Edwards, loc. cit. 



« Savigny, Mem. &c. I. PI. VI. fig. 2, d. 



^ It is well known that the Scorpionidae and 

 the other rapacious Arachnoidae, merely suck 

 their prey ; but it is said that Galeodes devours 

 completely the insects which it has caught, seizing 

 them with their cheliceres, and eating tliem piece 

 by piece. During tliese processes each chelicere 

 acts separately (Hutton, Ann. of Nat. Ilist. XII. 

 1843, p. 81, or Froriep's neue Not. X.XVIII. p. 

 49). The Phalangidae have probably the same 

 habits, for fragments of insects which they have 

 eaten are found in their digestive canal \Tulk, 

 loc. cit. p. 248). 



8 See Roesel, loc. cit. Taf. XXXVII., and Sa- 

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

 onet, loc. cit. PI. XIX.. XXI. 



