96 Messrs. C. B. Williams and P. A. Buxton on 



without their aid. The photographs (PL IX and X) 

 show the position in which the Mantis remained during the 

 whole process, and Adair (1914, I, p. 120) cut off the wings 

 of one specimen which was laying its eggs, in order to get 

 a better view, without disturbing the Mantis or the con- 

 struction of the ootheca. In view, however, of the definite 

 statements of Brongniart (I.e., p. 449), Perrier (1870) and 

 Giardina (1899, p. 311), it seems possible that occasionally 

 the elytra may assist. In any case, the view of Perrier 

 and Giardina that the longitudinal furrows on each side 

 of the dorsal flaps are due to the pressure of the elytra 

 is unsound, and still more so the ingenious theory of the 

 latter author, that the exit passage and protective flap are 

 formed by the insertion of the elytra and hind-wing, for 

 our ootheca, constructed entirely without their aid, has 

 all these features in a normal condition. It occurs to us 

 that when the insect is upside down the wings might be 

 used to prevent the freshly secreted material from flowing 

 away, but even at this stage it is not very liquid. 



In the construction of the ootheca the tip of the abdomen 

 goes through a regular cycle of movements, each repetition 

 resulting in the laying of one group of eggs and the formation 

 of the corresponding portion of the ootheca.* This cycle 

 is shown diagrammatically at text fig. 3, which represents 

 the face of the ootheca under construction (seen from the 

 direction of the insect). This face is not flat but concave, 

 being most sharply curved in a vertical plane, as may be 

 seen in the partially constructed ootheca in PL X, 1, and 

 also in sections of the completed ootheca, text fig. 2, II, by 

 the curve of the divisional wall. The movements are as 

 follows : When the insect has finished laying a group of 

 eggs at A, on the left-hand side, the tip of the abdomen 

 is moved with a slight curve to the top of the right-hand 

 side of the ootheca, and then slowly down to the bottom 

 along the periphery. During this movement the gono- 

 pophyses may be seen moving rapidly backwards and 

 forwards just beneath the slightly hardened outer skin. 

 By this process the gum in the outer layer is more vacuo- 

 lated, the divisional transverse wall N in this area formed, 



* Giardina (1899, p. 147) states that all the eggs and thecal 

 material on one side of the ootheca are secreted by the corre- 

 sponding ovary and colleterial gland. He gives no evidence for 

 this, and we saw nothing in the construction that would necessitate 

 this assumption. 



