NEQEOPTERA— PLANIPENNIA— SIALINA. 153 



as man}- parts as there are eggs, the interovuUir fibrous material extending 

 to the surface of the ootheea, forming- walls to deep cells which contain 

 eggs, and which are corked up, as it were, liy plugs of albuminous material. 

 These plugs seem to be very similar to the cell-walls, having been com- 

 posed apparently of viscous threads, also running in the same direction as 

 the longitudinal axis of the egg ; but in some cases the cell-walls beyond 

 the eggs have become blackened, while the plugs retain their normal color 

 and separate readily from them. 



When the egg-mass was undisturbed, the outermost eggs lay horizon- 

 tally, and those next the median furrow vertically (Fig. 15) ; the division 

 walls of the cells were therefore thinnest below, and it appears probable 

 that the young made their escape at the bottom of the median furrow, where 

 the outer coating is also thinnest, though not so presented in the schematic 

 figure. Where double layers occur, the eggs of the upper seem to be in a 

 direct line with those of the lower layer, egg for egg, as if a cell of double 

 length were stocked with two eggs, separated by an albuminous partition, 

 and in this case the albuminous floor and covering are thinner than usual, 

 so that the egg-mass is not greatly enlarged nor distorted. When two 

 la3'ers were thus formed, the young larva^ of the upper layer must have 

 escaped through the emptied cells of the lower. 



It only remains to add that with a single exception these masses differ 

 comparatively little in size, most of them being nearly or quite five centi- 

 meters long, although some scarcely exceed four centimeters. The single 

 exception is of a mass only a little more than fifteen millimeters long, six 

 millimeters Ijroad, and three millimeters high. It shows no fuxTOw, but 

 may represent only one lateral half of an egg-mass, as the walls of one 

 side are steeper than those of the other and look like the sides of a 

 . median furrow. This mass is so small that only by presuming one-half 

 to be gone and the albuminous covering to be thinner than usual can it 

 be regarded as belonging to the same species with the others, although 

 evidently of a similar nature. In case it belongs to the same species, it 

 may be looked upon as probable that a female usually deposited all hei' 

 eggs in a single bunch, but that in this case some accident preventing it, 

 the remnant was subsequently laid in a mass of much smaller dimensions, 

 one-half of which is preserved. This is the view I am disposed to adopt. 



Crow Creek, near Greeley, Colorado (Laramie group). Th: C. A. 

 White. Many specimens. 



