586 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 51. 



The type material is from Portland, Oregon, September 2, 1915, 

 from wild cherry (Prunus, species), collected by the author. The 

 species is nearest T. monticolus, herein described, from which it is 

 readily separable through the collar trachea and penis characters. 



TETRANYCHUS WILLAMETTEI, new species. 



Color, pale lemon-yellow. Eyes single on each side. Legs and 

 palpi, pale color. Dorsal bristles not arismg from tubercles. Body 

 of female eUiptical, four-fifths again as long as broad, widest between 

 legs III; length, 0.25 mm.; breadth, 0,14 mm. Bristles, about 22, 

 in four dorsal rows, the longest about half the width of the body. 

 Mandibular plate with parallel sides, 2| as long as broad, rounded at 

 tip with no emargination visible. "Thumb" of palpus of very unus- 

 ual form — semispherical or subcorneal, bearing at its tip a very 

 slender, long " finger" ; on its upper side near apex are two pin-shaped 

 pseudo-fingers, and on same side about midway to base is a "finger" 

 shorter and even thinner than terminal "finger;" between this and 

 base are two slender hairs a trifle longer than subbasal "finger"; a 

 slender hair arises latero-ventraUy one-third the distance from tip to 

 base of " thumb." The claw on the penultimate joint does not reach 

 to subbasal "finger." The legs are rather short; forelegs about four- 

 fifths the length of body. Femur about two and one-half times as 

 long as thick, barely longer than the tarsus; tibia, and patella equal. 

 Tip of tarsus bears a claw which is rather strongly bent near base and 

 only slightly arched for the rest of its lentgh; it appears to be uncleft 

 for over half its length, and then divided into six closely appressed 

 spines. The usual series of four capitate (tenent) hairs arise in pairs 

 by the sides of the claw base. The coUar trachea, opening medially 

 in a pore, runs first downward and backward, then upward and 

 backward, and then upward and shghtly forward. It is of nearly even 

 caHber throughout, but gradually enlarges a trifle toward the hind 

 end. Viewed as a whole it is very nearly sickle-shaped. The penis 

 is simple in structure, the shaft being very gradually attenuated to 

 an extremely sharp point; it is very shghtly bent just distad to the 

 middle, but is generally straight. 



Type.— C&t. No. 20169, U.S.N.M. 



The type material is from Oregon City, Oregon, August 22, 1915, 

 from the leaves of the white oak (Quercus lohata), collected by the 

 author. The presence of this species on oaks is revealed from a dis- 

 tance through the rusty appearance. The species appears to be 

 quite aberrant, but finds its nearest ally, perhaps, in NeotetranycJius 

 rubi of Trag&rdh. 



TETRANYCHUS ILICIS, new species. 



Color, from ferruginous to reddish-brown, with a pale pink area 

 embracing central portion of the cephalo thorax; darker than most 

 red spider species. Eyes conspicuous, carmine. Dorsal bristles 



