18C8.] 385 [Scudder. 



he retained the name of Gryllotalpa, under which all the 

 species had formerly been grouped, and to the other applied 

 that of Scapteriscus ; these two groups were separated by 

 the following characteristics. 



In Scapteriscus the posterior margin of the sternum of the eighth 

 abdominal segment of the S is produced into a stout prominent cen- 

 tral tooth ; in Gryllotalpa tlie margin is entire. 



The mesosternal ridge of GnjUotalpa is prominent, and almost 

 equally so throughout; that of Scapteriscus is never prominent on the 

 anterior half of the segment, and is often limited to the jjosterior 

 half, or is even obsolescent. 



The fore trochanter of Scapteriscus is large; the free jiortion 

 almost always equals the tibial dactyl in length, and is of about the 

 same size at the tip as at the base; that of Gryllotalpa is proportion- 

 ally small, seldom exceeding hah" the length of the tibial dactyls ; the 

 form is cultrate or lenticular. 



Scapteriscus is furnished with only two fore-tibial dactyls, both of 

 which are movable; Gryllotalpa has two movable dactyls besides a 

 second pair Avhich are immovable. 



With but few exceptions, the hind femora of Scapteriscus more 

 than equal the pronotum in length, Avhile in Gryllolalpa they are 

 always shorter than the pronotum. 



In GryllotaJpu the length of all the hind tarsal joints taken together 

 seldom exceeds half the width of the pronotum, while they ecpial its 

 whole width in Scapteriscus. 



The hind tarsal claws of Scapteriscus are clothed with short hairs 

 nearly to the tip; those of Gryllotalpja have hairs only at the base. 



Tlie tegminaof Scapteriscus, with but few exceptions, cover, when 

 at rest, two-thirds of the abdomen ; in Gryllotalpa they seldom con- 

 ceal more than one-half of the abdomen. 



The nerviu'es of the middle field of the tegmina in the females of 

 Gryllotalpa are distant and rather irregular, somewhat resembling 

 those of the males ; in Scapteriscus they are approximate, regular 

 and straight. 



The anal cerci are longer than the pronotum in Gryllotalpa ; shorter 

 in Scapteriscus. 



Finally, the ninth, and sometimes the eighth abdominal segments 

 are furnished above, in Gryllotalpa, with two transverse lateral rows 

 of long hairs directed inwards, as if to keep the long folded wings in 

 place; these are absent from Scapteriscus, where the wings are 

 equally long and similarly folded. 



Only one species of Scapteriscus has been found without the limits 

 of South and Central America, and that — occumng in a single in- 



rnOCEEDINGS B. S. N. H. — VOL. XI. 25 APRIL, 1868. 



