468 



LECTURE XIX. 



Levigrada. 



Legs much developed ; abdomen rudimentary : 



bisexual. 

 Genera Pycnogonum, Nymphon, Ammothea, Pal- 



lene, Phoxichilus. 



Order Trachearia. 



Cephalothorax one or 



Respiratory organs consisting of tracheae. 

 two articulated. Bisexual. 



A. AcARiNA. Abdomen unarticulated and fused with the cepha- 



lothorax. Palpi simple. 

 AcARiD^. Genera Sarcoptes, Glycyphagus, Tyroglyphus, 



MelichareSy Acarus, Pteroptus. 

 Genera Limnochares^ Arrenurus, Diplodontus, 



Hydrachna, Atax. 

 Genera Hoplophora, Oribates, Pelops, Damceiis. 

 Genera Dermanyssus, Uropoda, GamasuSy Argus. 

 Genus Ixodes. 

 Genera Bdella, Molgus. 

 Genera Erythrceus^ Trombidium, Smaridia, Te- 



tranychus, Rhyncholophus, PeiUhaleus. 

 Abdomen articulated, but indistinctly separated 



from the cephalothorax. Palpi simple. 

 Genera Phalangium, Gonyleptes^ Eusarcus. 



C. PsEUDOSCORPn. Abdomen articulated, but indistinctly separated 



from the cephalothorax. Palpi forficulate. 

 Genera Obism?n, Chelife7\ 



D. SoLPUGii. Abdomen articulated, distinctly separated from 



the cephalothorax. Palpi simple. 

 Genus Galeodes. 



Hydra chnidje. 

 Oribatibm. 



GAMASIDm. 



ixobibje. 



Bdelbibm. 



Trombibibm. 



B. Opilionixa. 



Order Pulmotracheaeia. 

 Respiratory organs consisting of tracheae and pulmonary sacs. Ab- 

 domen and cephalothorax unarticulated, distinct from each other. 



Nat ANTES. 

 Sedentes. 



Errantes. 



VaG ANTES, 



VeN ANTES. 



Genus Argyroneta. 



Genera Theridion, Episina, Linyphia, Zosis, Ulo- 



borus, Tetragiiatha, Epeha, JVyssus, Agelena, 



Lachesis, Tegenaria. 

 Genera Artema, Pholcus, Latrodictus, Clotho, 



Brassus, Clubio?ia. 

 Genera Clastes, Sparassus, Philodromus, Eripus, 



Seleiiops, Tho??iisns, Delejia. 

 Genera Attus, 3Iyrmecia, Dolophenes^ Sphasus, 



Ctenus, Dolomedes, Lycosa^ Omosites, Seges- 



