BITHYS QUERCUS. 241 



arrangement ; beneath are similar cells, but of larger size and higher 

 walls, so that one doubts whether they are sculptures of the shell proper 

 or belong to the superficial system, but the continuity of their walls 

 with the superficial layers at the margin, and with similar material 

 that lies thicker in places to attach the egg as a cement to the surface 

 from which the egg has been detached, seems to show that they are of 

 the superficial layer ; they are of fairly hexagonal form, tbeir diameter 

 is about O02mm. There remains to be described what passes for the 

 most part as the e°fg, i.e., the beautiful sculpturing of the superficial 

 corky layer. Of the eggs collected, the darkest have this considerably 

 damaged, tending to show this was white when fresh, several, how- 

 ever, seem quite perfect. Where best developed, round the shoulder of 

 the egg, this is arranged as high narrow walls enclosing triangular 

 cells ; at the angles of intersection are raised pillars with thickened 

 summits ; the walls sag a little between these points. As compared 

 with other Ruralid eggs, the chief feature is that the walls seem to 

 be of uniform thickness from top to bottom, and that the bottom of 

 the cells is the eggshell proper, or, if covered by the adventitious, then 

 thinly and uniformly, with no thickening or spreading out of the walls 

 of the cells. Round the micropylar hollow the arrangement is the 

 same, and looks as if this layer were cut off abruptly at its margin, 

 the ends against it having very little rounding, and each wall a little 

 thickened ending separately. Though the arrangement is the same, it 

 is curiously modified, the cells being lengthened radially and narrowed 

 across, just as the meshes of a net are altered, if drawn together at 

 the top of a bag. In these lengthened meshes the transverse walls are 

 wanting centrally, and out to where the wall of the egg begins to 

 slope (if the diameter of the egg be divided into four, the egg is nearly 

 flat, over the two middle ones). It results from the central gathering- 

 in process that about 35 ribs end suddenly against the micropylar 

 hollow, and hardly more cells are found in a circle a little above the 

 margin of the egg. The pillars on the intersection of the ribs 

 or walls form a diamond pattern (two triangles) above, more 

 strictly triangular round the margin. Radially, they are about 

 O09mm. apart, circumferentially less, about O06mm. at the margin of 

 the flat top, about O08mm., both ways, marginally. They are ranged in 

 line, radially, at these distances, alternating in neighbouring rows, but 

 are closer in oblique rows (either way) (engine-turning pattern) 

 (Chapman). Echinoid in appearance. In outline (when viewed 

 laterally) a depressed cylinder with rounded edges. Length : breadth : 

 height, as about 2:2:1, forming roughly a squat oval in vertical, and 

 a circle, of -8mm. diameter, in horizontal, section. Its colour is of a 

 yellowish milk-white, somewhat waxen in appearance. The surface is 

 covered with a rough, raised reticulation, formed by two oblique series 

 of curved ribs running from the edge of the apical depression to the 

 base, in opposite directions, thus cutting each other and covering the 

 surface with irregularly-formed diamond-shaped cells, with the cross- 

 points forming markedly prominent knobs ; or the surface maybe likened 

 to a chain-harrow, in which the blunted teeth (or tines) extend centri- 

 fugally, with no regular arrangement of the processes. The apical 

 depression is somewhat hexagonal in shape, its base pitted ; the micro- 

 pylar rosette, placed centrally in the hollow, also hexagonal ; the 

 diameter of the apical depression about one-fifth the equatorial 



