1913] Taxonomic Characters in Tetranychus. 459 



inent, slightly swollen at its anterior end; in size, smaller than the basilar 

 lobe of shaft. Shaft long, curved, and resembling the sting of a wasp; 

 varying greatly in curvature, generally bending downward, then up- 

 ward, or it may have but a single curve, or it might be straight. Basilar 

 lobe, large, subcylindrical, equal to over one fourth of the total length 

 of the entire shaft. Hook and barb absent. 



Generally distributed over Hood River Valley, Oregon; on 

 apple trees especially; observed and reported by many people. 

 Found in some places in the Willamette Valley, Oregon; on 

 apples ; by the writer. Probably present throughout the Pacific 

 Northwest above altitudes of 1000 feet. 



Tetranychus pratensis Banks. 



Tetranychus pratensis Banks — Proc. Entom. Soc. Wash., Vol. XIV, p. 97. (1912). 



I have examined specimens of this species, and find that the 

 tarsal appendages are very peculiar. I find that there are two 

 claws as stated by Banks, but only one, the outer, is simple. 

 The inner claw is bent downward very near its base, and beyond 

 this bend it is three cleft. On each side of the tarsal claws is a 

 short projection from which extends a pair of tenent hairs. The 

 penis of the male may be described as follows : 



Inner lobe slightly over one half as long as the shaft of the penis. 

 Shaft stout, somewhat similar to the shaft in T. telariiis Linn. ; enlarged 

 slightly at its base so as to form the basilar lobe. Hook pronounced; 

 bent at an angle of about 90° to the axis of the shaft. Barb absent. 



From "Pullman, Washington; on timothy; by G. R. Hyslop. 



Tetranychus mytilaspidis Riley. 



Penthalodes mytilaspidis Riley — Hubbard, Orange Insects, p. 216. (1885). 



This very characteristic red spider differs from most of our 

 species in having the bristles of the body arising from prominent 

 tubercles. In many respects it is about as far removed from 

 T. telarius Linn, as any of the species of the genus. In the 

 characteristics of the male genital armature it appears to be 

 rather closely related to T. telarius Linn. The penis may be 

 described as follows : 



Inner lobe about one and a half times as long as the penis proper; 

 not swollen at its anterior end. Shaft very short, and stout. A basilar 

 lobe present in the form of a stout, more or less hook-like, protuberance 

 on the dorsal side of the shaft. In this respect the penis is like that of 

 T. telarius Linn. Hook very large, stout; bent at an angle of from 30° 

 to 50° degrees to the axis of the shaft. Barb absent, but the distal part 

 of the hook is bent out considerably. 



