Two remarkable forms of Manticl oothecae. 513 



the sides of the capsule are forced apart and the larvae are 

 liberated. 



But the larvae of the Mantidae that formed the remark- 

 able oothecae described in this paper, when they throw off 

 their eg^ membranes are in very different case, for they 

 find themselves in a relatively vast and empty space, the 

 walls of which are both tough and smooth. They can 

 find no ]point cTappui whence they can exert pressure on 

 the oothecal wall, and it is difficult to see how with their 

 tender mandibles they can gnaw their way through this 

 resistant tissue. At one time I was inclined to believe 

 that the ridge on the East African oothecae was a line of 

 dehiscence and marked, so to speak, the line of least resist- 

 ance in the structure. But this is not so, the ridge is the 

 toughest part of all, and even if it was a line of dehiscence, 

 where is this line in the South American specimen ? For 

 the release of the larvae, then, either the bladder-like 

 oothecae must crack open at the propitious moment, or, as 

 appears more probable, the larvae are provided with some 

 special organ that enables them to pierce or rasp a way 

 through the walls of their prisons. 



The grooved ridge on the East African ootheca deserves 

 another word of notice. Superficially it resembles the 

 grooved ridge on the ootheca of Ameles and might be 

 regarded as formed in a similar way. But this cannot be 

 so. The ridge of the ootheca of Ameles is the product 

 of the free ends of the lamellae forming the walls of 

 the egg-cells; as each cell is made and each egg laid a 

 portion of the ridge is formed and its construction pro- 

 ceeds ^an j^assw with the growth in size of the ootheca. 

 It is plain, therefore, that each element or division of 

 the ridge is in direct relation with an egg and egg-cell. 

 The ridge in the African oothecae is, as stated, made up 

 of a double series of compartments, but these compart- 

 ments bear no relation to the internal structure of the 

 ootheca. The septum is homogeneous and shows no trace 

 of the segmental arrangement characteristic of the internal 

 structure of the ootheca of other Mantidae. Moreover, the 

 •eggs not only lie at right angles to the direction of the 

 ridge, instead of in the same plane as in Ameles, but are 

 also much more numerous than the compartments of the 

 ridge, and the number of rows in which they are arranged 

 is less than the number of compartments. It seems, then, 

 .almost certain that this grooved ridge is functionless as 



