218 ARACHNIDES. 



Sometimes these Ticks, with eiglit legs and without chelicerae, 

 have no eyes that are perceptible; their palpi are either anterior and 

 projecting, but in the form of valvulae, widened or dilated near the 

 extremity, serving as a sheath to the sucker — or inferior; the parts 

 composing the sucker are horny, very hard and dentated; the body 

 is invested with a coriaceous skin, or has at least, anteriorly, a scaly 

 plate. 



These animals are parasitical, gorge themselves with the blood 

 of several of the Vertebrata, and from being extremely flat, acquire 

 by suction a great volume and a vesicular form. They are round or 

 oval. 



Ixodes, Lat. Fab. — Cynorhasstes, Herm. 



The palpi forming a sheath to the sucker, and with it constituting 

 a projecting and short rostrum, truncated and slightly dilated at the 

 extremity. 



The Ixodes are found in thick woods abounding in brushes, briars. 

 Sec; they hook themselves to low plants by the hind legs, keeping 

 the oihers extended, and fasten on Dogs, Oxen, Horses and other 

 Quadrupeds, and even on the Tortoise, burying their sucker so com- 

 pletely in their flesh, that they can only be detached by force, and by 

 tearing out the portion that adheres to it. They lay a prodigious 

 quantity of eggs, which, according to M. Chabrier, are protruded 

 from their mouth. They sometimes increase to such an enormous 

 extent on the Ox and Horse, that they perish from the exhaustion. 

 Their tarsi are terminated by two hooks inserted in a palette, or 

 united at base on a common pedicle.* 



The ancients designated these Arachnides by the term Ricinus. 

 Huntsmen in France call the species which attaches itself to the 

 Dog, Louvette. It is the 



Ixodes ricinus; Acarus ricinus^ L.; Meatus reduvius, De Geer, 

 Insect,, VII, vi, 1, 2. A deep blood-red; the scaly, anterior 

 plate still darker; sides of the body turned up, and slightly 

 hairy; palpi forming a sheath to the sucker. 



Ixodes reticulaius, Lat. Fab.; Acarus reduvius, Schrank, 

 Enum. Insect., Aust., No. 1043, iii, 1, 2: Cynorhxstes pictus^ 

 Herm. Cinereous, with small reddish-brown spots, and little 

 annular lines of the same colour; edges of the abdomen striate; 

 palpi nearly oval. It infests Oxen, and when tumefied, is six 

 lines in length. 

 The species of this genus have not been sufficiently studied(l). 



(1) Jlcarus asgyptiits, L. ; Herm. Mem. Apter., IV, 9; L. IV, 13; — Acarus rhino- 

 eerotis, De Geer, Insect., VII, xxxviii, 5, 6; — Acarus americanus, L.; — Ac. nigua, 



