660 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.59. 



OLIGONYCHUS AMERICANUS, new species. 



Plate 125, fig. 1. 



A small species. Preserved specimens yellowish and not showing 

 maculations. Mandibular plate broad, being about two-fifths as 

 broad as long, not emarginate in front but with a deep V-shaped 

 notch behind. Palpal thumb not swollen and not exceeding palpal 

 claw; terminal finger moderate, about one-third as broad as thumb. 

 Legs moderate; anterior pair exceeding the palpi by half their 

 length; posterior pair extending beyond the tip of abdomen by the 

 full length of tarsi and one-half the length of their tibiae. Simple 

 claw of each tarsus almost as long as width of tarsus, with basal half 

 but slightly and distal half strongly curved; deflexed claw about 

 half as long and half as thick as simple claw, and with at least three 

 hair-like barbs on its outer side. Length, 0.32 mm.; width, 0.19 mm. 



Type locality. — Experimental Farm, Saskatchewan, Canada. 



Type slide.— Cat, No. 24026, U.S.N.M. 



Described from specimens on a single type slide. This species 

 differs from 0. minimus Targioni-Tozzetti in having the deflexed 

 claw pectinate on the outside and from the following new species, 

 to be described,* in being much smaller, more slender, and in its 

 habits. The species occurs on leaves of spruce and does considerable 

 injury. 



OLIGONYCHUS MAJOR, new species. 



Plate 125, fig. 2. 



Preserved specimens yellowish, or yellowish brown; body clothed 

 with conspicuous minutely pectinate, curved setae. Mandibular 

 plate about one-half as broad as long, not emarginate in front, but 

 with a deep V-shaped notch behind. Thumb of palpus not sur- 

 passing claw; -apical finger medium in thickness, slightly over one- 

 third the width of thumb. Legs medium; anterior pair extending 

 beyond tips of palpi by over one-half their length; posterior pair 

 extending beyond the tip of abdomen by length of tarsi only. Simple 

 tarsal claw scarcely as long as width of tarsus; slightly curved near 

 its base, but strongly curved toward its tip; deflexed claw about 

 one-half as stout and two-thirds as long as simple claw and with 

 three to five prongs on outer side. Tenent hairs exceeding simple 

 claw by almost one-half their length and terminated with distinct 

 knobs. Length, 0.35 mm.; width, 0.21 mm. 



Type locality. — Yarrow Experiment Station, Rockville, Maryland. 



Type slide.— Cat. No. 24027, U.S.N.M. 



Described from specimens on type slide. This species is very 

 similar to 0. americanus, but is much larger and of a different shape, 

 and occurs on a host not closely related to the host of the latter. 

 This species infests the avocado. 



