42 WHEELER. [Vol. VIII. 



germ-band is relatively much larger when compared with the 

 yolk-mass than the germ-band of Staginoviantis . It arises on 

 the ventral surface very near the lower pole. That such is the 

 correct position of the embryo may be easily ascertained, since 

 the mother-insect thrusts her eggs into the ground with their 

 long axes perpendicular to the surface. In a glass jar con- 

 taining a few inches of earth, many eggs were deposited 

 between the surface of the glass and the earth, so that the 

 exact position of the apical pole could be noted, and the ^^^ 

 removed and hardened with this pole constantly in sight. Thus 

 it was possible to determine the exact topographical relations 

 of the embryo to the yolk throughout the important stages of 

 early development. 



During gastrulation the germ-band of Grylliis (Fig. 13) is 

 more elliptical and somewhat narrower than the germ-band of 

 Stagnioniantis. Its edges are also distinctly marked off from 

 the blastoderm and here, too, the amnio-serosal fold {avis) 

 arises along the entire periphery. The blastopore {bl) is much 

 narrower than the corresponding depression in Stagnioniantis. 

 It is deepest posteriorly. 



The discovery of an invaginate gastrula in Gryllns made it 

 extremely probable that this stage had been overlooked in the 

 other members of the same family which have been studied 

 from an embryological standpoint. Neither Korotneff in his 

 study of Gryllotalpa ('85), nor Ayers in his study of Qlcanthus 

 ('84), succeeded in finding an invagination. I was unable to 

 secure the eggs of any of our native GiyllotalpcE, but I col- 

 lected a great number of CEcantJius eggs in Ohio during the last 

 days of September, An examination of these soon convinced 

 me that Ayers had not seen the youngest stages in the develop- 

 ment of the germ-band. The youngest germ-band that he 

 figures (Figs. 1-18) lies near the posterior end of the egg 

 with its tail pointing towards the micropylar pole. According 

 to Ayers " A tract of the blastoderm along the median line of 

 the ventral (concave) side, lying nearest the deep or primitively 

 head-end of the egg, becomes thickened into a germinal band, 

 which is the first trace of the body of the embryo." But this is 

 not the first trace of the body of the embryo, nor does it 



