52 



A NEW NOMENCLATURE FOR THE BROODS OF THE PERIODICAL 



CICADA. 



By C. L. Marl att. 



The writer reviewed the different nomenclatures suggested by various 

 authors for the broods of the periodical Cicada in Bulletin Xo. 14, new 

 series, of the Division of Entomology, and therefore a brief summary 

 of the old systems is all that need be given here. 



It will be remembered that the earlier writers, viz, Prof. Nat. Potter, 

 Dr. William T. Harris, and Dr. G. B. Smith, classified the broods solely 

 according to the years of their appearance. The unpublished register 

 left by Dr. Smith includes every brood now known classified according 

 to race, and gives the localities for one additional brood, the existence 

 of which seems not to have been confirmed. Though lacking any spe- 

 cial designation for the broods, Dr. Smith's classification is as complete 

 and accurate as that published by Dr. Riley and since followed by all 

 later writers. Dr. Asa Fitch was the first to introduce a numbering 

 system for the different broods, enumerating nine altogether, but his 

 data was very limited and he was not aware of the 13-year southern 

 period, and there necessarily resulted no little confusion of the broods 

 of the two races. The Walsh-Riley enumeration of 1868 gave the 

 records for sixteen broods, which were designated by roman numerals 

 from I to XVI, the enumeration being based on the sequence of the 

 different broods after 1868. In 1869, in his First Missouri Report, Dr. 

 Riley, having in the meantime secured the manuscript paper of Dr. 

 Smith, added the six broods lroin this paper not represented in the 

 Walsh-Riley enumeration, increasing the number of the broods to XXII, 

 and renumbered them again in accordance with their sequence, begin- 

 ning with 1869. Several of these broods are rather unimportant, or 

 lack confirmation, and one of them, Brood III, was founded on an erro- 

 neous record and has been dropped. 



In the enumeration of the broods by Walsh-Riley, and later by Riley, the 

 two races are mixed together and a sequence of numbers given, which, 

 after the first thirteen years, lost all significance as a record of the order 

 of the broods in time of appearance, aud from the first obscured the true 

 kinship of the broods in each race. If, on the other hand, each race be 

 considered separately and its broods be arranged in a series in accord- 

 ance with their sequence in time, an important natural relationship in 

 point of origin and distribution is plainly indicated. 



Taking first the broods of the 17-year race, it will be seen from the 

 subjoined table that if the enumeration begin with Brood XI, the 

 17-year broods follow each other in regular succession for eleven con- 

 secutive years ; then after a break of one year follows Broods V and 

 VIII, and after another break of one year, Brood IX ; another break 



