No. I.] CONTRIBUTION TO INSECT EMBRYOLOGY. 73 



Graber has paid no attention to the movements of the Steno- 

 bothrus embryo, and as he most assuredly has not demonstrated 

 from a careful study of the later stages that the lamella in 

 question is really converted into the dorsal wall, I cannot 

 attribute much value to his observation. 



The foregoing observations go to show that the blastokinetic 

 processes are essentially the same throughout the suborder 

 Saltatoria. Each family presents certain deviations from the 

 type, which is probably most closely adhered to in the Gryllidae. 

 Anatrepsis is aberrant in the Locustidse, while the Acrididse 

 are aberrant in the tardy separation of the procephaleum from 

 the lower pole. Notwithstanding these deviations the Salta- 

 toria form a clearly circumscribed group embryologically as 

 well as anatomically, and were it not for Gryllotalpa would be 

 separated by a wide gap from all other Orthoptera. Gryllo- 

 talpa is a generalized form, as Brauer has pointed out from 

 a study of its anatomical peculiarities ('86), and his conclusions 

 are to some extent substantiated by the large size of the germ- 

 band as compared with the yolk mass. 



In the Cursoria, as represented by Blatta germanica, move- 

 ments of the embryo are far less apparent. The germ-band 

 never leaves the ventral surface, on the middle of which it first 

 appears. I have shown, nevertheless ('89, text-figures, p. 348), 

 that it moves down the yolk after the rupture of the envelopes 

 till its tail reaches the lower pole. The tail then remains sta- 

 tionary, while the head gradually rises to the cephalic pole as 

 the body walls develop and invest more and more of the yolk. 

 Slight as are these movements, they nevertheless recall the 

 blastokinesis of the Saltatoria. I would regard the movement 

 of the whole Blatta embryo towards the caudal pole as ana- 

 treptic ; katatrepsis is probably represented only by the up- 

 ward growth of the embryo. The very late occurrence of the 

 former movement may be due to its rudimental character, since 

 it is too weak to carry the germ-band around the caudal pole. 



Few observations have been published on the relations of 

 the embryo to the yolk in the Gressoria. In Mantis, as I have 

 shown, the germ-band when first formed lies somewhat nearer 

 the posterior than the anterior pole. The embryo never leaves 



