CLASS TV. ACAT^r. 131 



Genus 1. TROMBIDIUM. Fair., Latr., Leach. 

 Tjegs eight. 

 Sp. 1. Ti-om. holosericeiim. Subqiiadrate, l)Ioo(l-rccl, tomentose; the 



down short composed of cyhndric papilke, which are rounded at 



their extremities. 

 Troml)idiiun holoscriceum. Fabr., Latr. 

 Inhabits Europe, and is abundant in the spring. 



Genus 2. OCYPETE. T^cach. 

 Legs six. 

 Sp. 1. Oct/, rubra. Red; back with a few long hairs, the legs witli 



many short hairs of a rufous ash-colour; eyes black brown. 

 Ocypete rubra. Leach, Trans. Linn. Soc. xi. 



This curious little animal, which is not larger than a grain of 

 small sand, is parasitic, and is tre(|ucntly to be found on the largest 

 tipuladous insects, adhering to their legs. No less than sixteen 

 specimens have been obtained from one insect. 



Fam. II. Gammasid^. Leach. 

 Palpi porrect, simple. 



Genus 3. GAM^NIASUS. Latreille, Leach. 

 Bodi/ depressed, the skin of the back partly or entirely coriaceous. 



* Anterior portion of the back, and a triangular part behind, cori- 

 aceous. 

 Sp. 1. Gamm. Cokoptratorum. Coriaceous parts of the back fuscous ; 



anterior pair of legs a little longer than the hinder ones. 

 Gammase des Coleopteres. Latr. Hist. Nat. dcs Crust, et des Lnsect. 

 vii. 399. Gammasus Coleoptratorum. Latr. Gen. Crust, et Insect, i. 

 117. Leach. Acarus Coleoptratorum. JJnn., Fabr. 

 Inhabits the excrements of horses and oxen, often attaching itself to 

 Scarabai, Histeres, &c. in great numbers. 



** Back entirely coriaceous. 

 Sp. 2. Gamm. marginatus. Ovate, brown ; belly coriaceous, the sides 

 alone membranaceous and whitish ; anterior legs nearly twice the 

 length of the body. 

 Inhabits dung and dead animals. 



Fam. III. AcAP.iDyE. Leach. 



Mouth furnished with mandibles : palpi simple, very short, not por- 

 rected. 



Genus 4. ORIBITA. Latreille, Leach. 

 Body covered by a coriaceous skin ; anterior part rostrated ; the pro- 

 duced part inclosing the organs of mastication : ahdome^i subglo- 

 bose : tarsi with claws. 

 Sp. 1. Or. geniculata. Fuscous-castaneous, shining, hairy: legs pale- 

 fuscous: thighs subclavate. 



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