4 Mr. F. j\Iuir and Dr. D. Sharp on 



the closure of the under-surface is eftected in the case of 

 A. puncticosia, but both are agreed that no special act of 

 intelligence is required to effect it. Mr. Muir thinks that 

 at the moment the abdomen has reached the limit of its 

 downward movement and is just turning upwards another 

 structure comes into play.* " Another plate in the abdo- 

 men, similar in form to the lower oothecal plate, comes into 

 play. It is similar in shape to the lower oothecal plate, 

 and passes over the newly-formed membrane, giving the 

 pressure necessary " to make this, while still soft, the re- 

 quisite shape, and also to make it retain by adhesion this 

 form and the position given to it. 



It appears possible, however, that the matter is even 

 simpler than this, and that the closure and consolidation of 

 the floor of the case may be due simply to the delay at the 

 moment of reversing the movement of the abdomen, sup- 

 plemented by the exudation, then, of a rather larger amount 

 of material, sufficient to fill any gap or irregularity; the 

 position given being maintained by the elasticity and 

 pressure of the parts previously constructed. 



With regard to the fact that the case is so constructed 

 as to leave an exit for the larva only above, and none below, 

 we may add that there does not appear to be any advan- 

 tasre in this limitation of modes of egress for the larva. 

 The advantage, if it existed, would consist in limitation of 

 modes of ingress for enemies. But in the case of the exits 

 that do exist, these are amply protected by the long free 

 ends of membranes curling over, while at the bottom it 

 will be recollected there are no free ends ; for each mem- 

 brane forms there a fold. It is the connections of, or between, 

 these folds that close the floor of the case and that have to bo 

 accounted for. See PI. I, fig. 9. 



The egg and membrane having been thus deposited, 

 another egg is placed by the side of the first (and of course 

 on the anterior face of the membrane), and the process is 

 repeated. The series of four rows of eggs is attained by 

 means of slight lateral movement of the abdomen, as will 

 be comprehended by the diagrammatic figure (fig. G, PI. I.) 

 showing the sequence of the position in which 8 suc- 

 cessive eggs are placed. It will be noticed that though 



* Mr. Muir considers that this is the 7th ventral plate of the abdo- 

 men ; plates 7-10 being, he considers, invagimited and used for these 

 mechanical purposes. 



