510 Mr. R. Shelford mi 



metrical way. When an ootheca is cut open a septum will 

 be seen dividing the oothecal cavity almost completely 

 into a right and left half; it extends inwards from 

 immediately below the ridge on the upper surface of the 

 oothecal wall towards the opposite wall, which, however, 

 it does not reach. The septum is a homogeneous vesicular 

 membrane of no great thickness but quite opaque ; its free 

 border is irregular in outline. The eggs are placed in 15 

 to 20 rows on either side of the septum with their long 

 axis at right angles to it and with the heads of the 

 embryoes directed outwards; they form two compact 

 masses which do not cover the whole of the septum but 

 only about a third of its surface, extending from the free 

 border towards the line of attachment. In one of the 

 larger oothecae there are 136 eggs situated on one side of 

 the septum and apparently an almost equal number are to 

 be found on the other side. There is no information 

 accompanying the specimens, so that it is not possible to 

 say if they were made by a single or by more than one 

 individual. 



The South American specimen is rather different in 

 appearance from the Delagoa Bay examples, though it is 

 built on essentially the same plan. It is almost a perfect 

 sphere, 15 mm. in diameter, hollow, dark green in colour 

 and semi-transparent ; its walls are quite smooth with the 

 exception of inconspicuous reticulations, and there is no 

 ridge as in the African specimens. The ootheca is borne 

 on a slender tubular stalk, and no doubt this was originally 

 attached to a twig, but it has been cut by the collector so 

 that the method of attachment cannot be determined now. 

 In the centre of this hollow sphere is an imperfectly 

 spherical mass of densely vesicular material like dried foam 

 in appearance. About 80 eggs are embedded in this mass, 

 they are set close together with the anterior pole directed 

 outwards and their arrangement is, roughly speaking, 

 radiate. This central ego^-mass is attached to the outer 

 wall of the ootheca by a thin septum which mcompletely 

 divides the ootheca into two halves ; the line of attach- 

 ment of this septum corresjjonds to that of the septum in 

 the East African oothecae and undoubtedly the two 

 structures are homologous. A few fragile strands of dried 

 foam help to moor the central egg-mass to the surrounding 

 wall of the ootheca. 



The accompanying diagrammatic figures of transverse 



