40 The Ohio Journal of Science [Vol. XVI, No. 2, 



It is sometimes stated that the distribution of gall insects 

 is similar to that of their host plants. In certain cases this does 

 not seem to be true. In that of my number 32 first found and 

 described by Sears, no report of this large and striking form has 

 appeared, showing it to occur east of the Allegheny mountain 

 system, a region in which //. ovata is abundant. In the cases 

 of my numbers 5, 9, 19 and 31, all heretofore unreported and 

 possessing prominent distinguishing characters, it would seem 

 as though they were somewhat restricted in their distribution, 

 for while comparatively common in Ohio, they are never seen 

 in Connecticut or Kansas, where equally intensive collecting 

 was prosecuted. So few are the students of cecidia and so 

 meager the data in this field, that it is, however, much too early 

 to make positive assertions in matters of geographic distribution. 



The data on the galls presented herewith was compiled 

 for the most part at the time of collection; the notes and draw- 

 ings made from fresh material. For later comparative work, 

 the material was all preserved in formalin, each collection 

 being assigned to a vial. 



The writer has refrained from attaching a specific name to 

 his new species of cecidia, a practice very common on the part 

 of European cecidologists. Even though the adult gall has no 

 direct relation to the adult insect, the fact, nevertheless, remains 

 that the specificity of the gall owes its origin to the specificity 

 of the physiological phenomena of the larval insect, and it is 

 this, which in the mind of the writer, gives pre-eminence to the 

 insect. The adult gall and the adult insect can be conceived 

 as arising from the same complex, the larva, the adult insect 

 bearing, however, a more intimate and direct relation to the 

 original source of events than the gall. In many cases the 

 adult insects offer characters, making possible the delimitation 

 of species, with greater exactness, than do the galls. For these 

 reasons new names of cecidia should only appear with adequate 

 descriptions of the cecidozoons. 



Though the galls almost uniformly occur on the under side 

 of the leaflet, the drawings have presented them in an inverted 

 position, with the gall uppermost, this being the position in 

 which the galls would be examined. In practically all cases 

 there are two sketches of the type, one showing the exterior 

 aspect of the gall, the other the interior as seen in a vertical, 

 median section. The figure number is in all cases the same as 

 the list number. 



