THI-: FEEDING OkdAXS Ul AUACIIXIDA, 

 INCLUDING MITES AND TICKS 



By R. E. SNODGRASS 



Collaborator, Bureau of Entomology and Plant Quarantine 



U. S. Department of Agriculture 



CONTENTS 



Pace 



Introduction i 



I. General discussion of arachnid structure 3 



The labrum and the epistome 5 



The chelicerae 6 



The pedipalps and the legs 8 



The mouth and the preoral cavity 14 



The sucking organ, or so-called pharynx 15 



Comparison of Arachnida and Xiphosurida 16 



The stomach and digestion 18 



II. The Palpigradi, or Microthelyphonida 19 



III. The Solpugida 22 



IV. The Pedipalpida 26 



V. The Ricinulei 3' 



\T. The Chelonethida, or Pseudoscorpionida 33 



VII. The Scorpionida 30 



VIII. The Phalangida, or Opiliones 43 



IX. The Araneida Si 



X. The Acarina 61 



Notostigmata 65 



Oribatoidea 67 



Holothyroidea 67 



Gamasides 69 



Ixodidae and Argasidae 7^ 



Trombidiformes 80 



.'\bbreviations used on the figures 86 



References ^ 



INTRODUCTION' 



Inasmuch as feeding is the function of prime imjxjrtancc with all 

 animals, it seems strange that no animals were originally endowed 

 with organs of feeding other than an intake opening into the alimen- 

 tary tract and a sucking device for the ingestion of nutrient material. 

 Primitive animals, therefore, swallowed water or mud and depended 

 for their subsistence on what organic matter might Ik therein con- 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 110, NO. 10 



