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hidiana University Studies 



narrow than in other varieties; anterior parallel lines posteriorly almost 

 entirely smooth, extending more than half way to the scutellum; whole 

 dorsal third of the mesopleurse smooth and naked; all coxag light rufous; 

 areolet moderately large, sometimes smaller than in 'polythyra; first 

 abscissa of the radius sharply angulate, with a short spur; length 2.5-3.2 

 mm., smaller than in any other variety. 



GALL. — Similar to the galls of other varieties, but distinct in being 

 elongate, rather regularly cylindrical, up to 15. mm. in diameter by 

 65. mm. in length. On Quercus Wislizenii. 



RANGE.— California: Mt. Tamalpais, Byron. 



TYPES. — 20 females, 2 galls. Holotype female, paratype females, 

 and gall at The American Museum of Natural History; paratype females 

 and gall with the author; paratype females at the U.S. National Museum 

 and Stanford University. Labelled Mt. Tamalpais, California; March 

 14, 1920; Q. Wislizenii; Kinsey collector. 



Insects emerged at some date after collecting the galls on 

 Mt. Tamalpais, on March 14, 1920. Galls collected a Httle 

 further south, at Byron on March 19, showed all of the insects 

 to have emerged earlier. 



This variety clearly belongs to this species, but is very 

 distinct from either of the Quercus agrifolia varieties. Host 

 isolation has accomplished more in this instance than the 

 geographic isolation of the agrifolia. varieties. 



I have a similar but shorter, generally smaller gall from 

 Wislizenii in the San Bernardinos, and at Three Rivers ; these 

 probably represent one or two other varieties related to 

 lustrior. A similar, still more elongate gall occurs on Quercus 

 Kelloggii. This oak is very closely related to Wislizenii, and 

 lustrior may sometimes occur on Kelloggii, but probably there 

 are other related varieties which extend into northern Cali- 

 fornia, Oregon, and the more northern range of the oak. 



Abnormal Galls of Plagiotrichus suttonii 



GALL. — Very slender, elongate steni: swelling, rather irregular, but 

 generally cylindrical, not over 8. mm. in diameter, but reaching 50. mm. 

 in length. Internally quite solid, woody, with a more or less continuous, 

 very irregular central cavity only incompletely divided into chambers; 

 without distinct larval cells. On Quercus agrifolia, Q. Wislizenii, and Q. 

 Kelloggii. 



This gall occurs thruout the range of the varieties of 

 suttonii. Nothing but inquilines is ever bred from it, and I 

 take it to be the inquiline-inhabited gall of suttonii, just as 

 inquiline-inhabited galls of Diplolepis tuberculatrix (Cock- 

 erell), of Diplolepis bicolor (Harris), and some others are dis- 



