48 
THE PERIODICAL CICADA. 
by retardation from Brood VII, o\nng to mountain conditions as 
affecting temperature. 
The widely separated swarm occurring on Marthas Vineyard has 
exceptional interest on account of the abundance of the insect and 
its extreme eastern location. This swarm has })een well recorded 
since the time of Harris, and in 1900, when it last appeared, was 
reported ])y Prof. H. T. Fernald as being as abundant as ever. 
Of the other scattering swarms the ones in western New York and 
in northern Illinois and in South Carolina are old records but ex- 
tremely doubtful, and possibly based on confusion of some annual 
species of Cicada with the periodical species. Xo confirmations of 
Fig. U. — Map showing distribution of Brood \"III. 1017. 
these records were obtained in 1900. New records were, however, 
obtained for New Jerse}^, Maryland, and North Carolina considera])ly 
away from the main body of the brood and very possibly having a 
different origin. None of the records in these three States represents 
important swarms, but merely scattering individuals. Some new 
records were obtained also in Ohio, Pennsylvania, and West Virginia, 
which, however, fall in with, the general range of the main body of the 
brood. 
The county indications in the list below are as with other recently 
studied broods, i. e., the star (*) means occurrence in swarms; italics, 
conffrmation of old records; and parentheses (), failure to secure such 
