544 [December 



they spring," lie can form in his mind's eye a complete idea of the an- 

 tenna, and an artist might even draw a very tolerably accurate picture 

 of it from the description alone. In a Synopsis, indeed, of species 

 already described, such diffuseness is not necessary, for we know where 

 to go for the full description ; but he that undertakes to describe new 

 species should endeavor to describe them in so full, definite and precise 

 a manner, as to comprehend every variety that can possibly come under 

 the notice of the student, and to separate his new species effectually 

 from all species already described or hereafter to be described. 



I regret much that, from the almost total lack of scientific facilities 

 in the Great West, I have been unable to compare the Willow-galls 

 now described with the published Willow-galls of Europe, so as to 

 decide the interesting question whether any of them are identical. To 

 the Eastern Pjutomologist, who lives, not in the backwoods but in a 

 civilized community, this would be comparatively an easy task and in- 

 deed almost a matter of course. To the Western Entomologist it is an 

 impossibility. Illinois, as the last Census shows, produces now more 

 maize and more wheat than any other State in the Union j and, as the 

 New York Market Reports show, she also produces more beef cattle 

 than any other State in the Union. But she has hitherto failed to 

 produce a single Public Scientific Library worthy of her wealth and 

 her great and growing resources. 



It is well known to Botanists that the genus Salix (willow) is a very 

 extensive and difficult one, and that authors have differed greatly as to 

 whether certain forms are true species or mere varieties. I am in- 

 debted to M. S. Bebb, Esq., of Washington, D. C, who has paid special 

 attention to this Botanical group, for naming the species found in this 

 vicinity from specimens which I had prepared for that express purpose. 

 The accurate determination of the species of our Willows is the more 

 valuable and important here, because I find it to be a very general, though 

 probably not a universal rule, that each gall-making insect confines itself 

 to a particular species of Willow. As to the larger and more abun- 

 dant and more conspicuous galls, such as Salicis brasslcoides n. sp., 

 S. rhodoides n. sp., S. strohiloides 0. S,, S. senigma n. sp. and S. 

 pomum n. sp., I am quite certain from long, close and continued obser- 

 vation, that the rule holds good universally so fiir as regards the seve- 

 ral species of Willow found near Rock Island. I have repeatedly, for 



