CERTAIN TAXONOMIC CHARACTERS OF GRYLLUS. 



for the ovipositor edaphic influences are more potent than differences 

 of the environment due to geographic position. This is strikingly 

 brought out when we compare the four Maine collections and also the 

 three from Cold Spring Harbor. 



The case of the wing-length is rather different. Table 11 shows the 

 relative abundance of the long-winged and the short-winged dimorphs 

 for a number of localities. Taxonomic literature is united in stating 

 that specimens of long-winged Grijllus are rare or lacking in northern 

 North America. They are practically absent from the vicinity of 

 Chicago, judging from extended collecting during three years. The 10 

 specimens I have from Fort Collins, Colorado, are all short-winged and, 

 as they are a museum lot, long- winged specimens would have been pre- 

 served had they been found; 25 of the 68 from Corvallis, Oregon, are 

 long-winged. I am not sure that the latter lot is a fair sample, being 

 a museum collection kindly given me. They, however, show that long- 

 winged individuals are common there. 



Considering these data, it seems that the long- winged form is char- 

 acteristic of warm, moist regions. Taxonomists bore witness to the 

 same thing in the related genus Gryllotalpa when they named the short- 

 winged form borealis. 



There is an interesting paleontological point which bears upon this 

 discussion. A number of crickets have been found in the Green River 

 deposits of Wyoming. They resemble the present-day crickets very 

 much and they are all long-winged. The Green River beds belong to 

 the Eocene epoch an epoch which evidently had a very mild if not 

 tropical climate. The long-wingedness of the crickets may be con- 

 nected with this fact. 



Considering only the short-winged group, we see in the mean wing- 

 lengths of the five collections from Massachusetts to Florida a gradual 

 increase as we go southward. In the Maine and Vermont collections- 

 excepting Perkins Cove and, possibly, Essex Junction the wing- 

 lengths, while longer than at Amherst, are shorter than in the other 

 collections from farther south. 



Many more collections are needed to establish a general law, but there 

 appears to be a tendency, not only for an increased percentage of 

 macropterous individuals with increased climatic heat (and moisture?), 

 but also for an increase in the size of the wings within the micropter- 

 ous group. Here again, however, local conditions overrule geographic 

 conditions. Witness the Perkins Cove, Maine, lot with 11 per cent 

 macropterous females and a micropterous group with an average wing- 

 length of 9.8 mm. 



The tegminal length is very closely correlated with the wing-length. 

 This is true in both the long-winged and the short-winged groups. It 



