114 U.S. NATIONAL MUSEUM BULLETIN 244 



bi- or tridentate, sometimes subacute; cell largely fuscous with 

 noticeable infusion of tawny scales along upper margin, in some 

 specimens invading almost half of cell; dark apical area beyond cell 

 abruptly fading to light brown along outer margin of wing; lighter 

 areas of forewing yellowish brown; M2 and 3 usually shortly stalked in 

 both fore- and hindwings, rarely connate or separate; spurs of 2A 

 absent. Secondaries almost invariably with cell Ri stalked, outer 

 radial crossvein rising beyond apex of discal cell; Sc usually with one 

 or two costal spurs; outer margin evenly rounded to slightly sinuate. 

 Wing expanse 35-32 mm. (x=39.35 mm., n=43).* 



Male genitalia. — (Fig. 290.) Valves with pulvilli reduced. 

 Aedeagus smoothly curved. 



Female. — Length 30-35 mm. As described for genus. 



Female genitalia. — (Fig. 309.) 



Case.— (Figs. 101, 102.) Length 55-100 mm.; diameter 11-15 

 mm. Spindle-shaped, usually ji of underlying silk surface exposed; 

 remainder of bag covered by several short sections of twigs arranged 

 longitudmally ; leaf fragments also may be attached. 



Type. — In the United States National Museum {0. townsendi and 

 0. bonniwelli). 



Type locality. — Las Cruces, New Mexico (0. townsendi) ; El Paso, 

 Texas (0. bonniwelli). 



Recorded hosts. — "Fabaceae: Rohinia sp." (Jones, 1928); 

 ''Prosopis odorata Torr. and Frem., Prosopis sp." (from specmien 

 labels) . 



Distribution.— (Map 12.) Known only from the Open Basin 

 Section of southern Arizona and New Mexico and the extreme western 

 part of Texas. 



Discussion.— On the basis of present knowledge, this species can 

 be divided into a subspecies of slightly larger moths, 0. t. dendro- 

 komos, inhabiting the Big Bend region of Texas, and a subspecies of 

 darker moths, 0. t. mexicanus, occurring farther south in central 

 Mexico. 



Material examined, — 45 cf cf , 2 99, 91 cases: 



UNITED STATES: Arizona: Chiricahua Mts., d', June 1-7, USNM. 

 Prescott, cT, USNM. Tucson, 4 cases, USNM. New Mexico: Specific locality 

 unknown, 2 ??, May 27, July 6, USNM. Las Cruces, 25 cf &, April 4-June 1; 

 cT, type, 0. townsendi, May 24; 50 cases, USNM; d', BM. Texas: El Paso, 

 13 cf cf , April 20-29; d, type, 0. bonniwelli; 2 cT d", 37 cases, USNM. 



♦Standard statistical symbols used in this paper: 

 x= sample mean 



n = total number of individuals measured 

 t= (sample mean minus population mean) divided by standard deviation 



of sample mean 

 P= probability 



