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sella. While lie was not able to observe the acts of pollination, all the 

 circumstances and the facts which he obtained would indicate that it 

 is ])recisely the same as described for other species of Yucca that are 

 fertilized by this moth, and the fertilized flowers show •' conclusively 

 that the pollen is thrust well into the stigmatal canal,'' or in some cases 

 apparently even into "the top of the ovarian cells, which owing to 

 the short style and the deep stigmatic notches, they [the moths] can 

 reach easily with their long maxillary tentacles." The moths taken from 

 flowers at Cabazon and San Diego are somewhat above the average in 

 size, with the horny and chitinous parts somewhat darker than in the 

 t>i)ical form, but specimens which he sent me can not be considered to 

 have even varietal differences and find their counterparts in my cabinet 

 in specimens from Dakota and Colorado. 



Yucca rupicola Scheele, of southern Texas, and Y. elata Engelm., ex- 

 tending from southern Texas to southern Arizona, are both pollinated 

 by Pronnba yi(ccaseUa, as Prof. Trelease ascertained. 



PRONUBA SYNTHETICA. 



Mr. Trelease was also fortunate enough to be able to study the opera- 

 tions of Pronhha synthetica on the flowers of Yucca brerifoUa. This 

 Pronuba is slower in its movements and slower to take flight than the 

 other species observed, though he found it more active during the daj' 

 than his Pronuba yuccaseUa. It takes wing less readily, and then 

 merely sails down to the ground. This indisposition to leave the flower 

 may be connected with the almost constant high winds on the Mojave 

 Desert, where this yucca most abounds. The fertilized pistils of this 

 Yucca are quite noticeable by comparison with those of other species 

 by their symmetry and lack of constriction or indentation, so uniformly 

 present in the Yuccas that are i)unctured by Pronuba yuccaseUa and P. 

 maculata. The explanation is found in the fact that Pronuba synthetica 

 pierces " the uppermost part of the style, conveying its eggs down to 

 the ovary through the stylar channel, the course followed by the pollen 

 tubes.'' This fact interested me very much, for I recollected very well 

 in my first studies of Pronuba yuccaseUa, before the act of oviposition 

 had been witnessed, that — puncturing for the purpose of ovipositiou 

 being unrecorded and therefore quite exceptional among Lepidoptera — 

 I was strongly of the oj)inion that the egg would be thrust through 

 the stigmatic opening down the stylar channel. The instinct to ovi- 

 posit only on the youngest flowers is ]>articularly marked in synthetica, 

 which Trelease frequently saw forcing itself into the narrow clefts 

 between the rigid sepals of the opening bud, the flattened form of the 

 insect facilitating the operation. This habit also suggests the cause of 

 the looseness of the wing scales and the ease with which they are lost. 

 Mr. Trelease's observations in detail on the actions of this Pronuba can 

 not Avell be condensed, and I quote them entire: 



Wheu about to deposit an egg, having selected a suitable flower, the female of 

 syxthetica runs to the bottom of the stamens much as yuccaseUa does, makes a rapid 



