1893.] Eggs of Pityophis Melanoleucus. 881 
brana putaminis of a bird’s egg. Here the shell is built up of 
a number of distinct laminz, in each of which the great bulk 
of the fibres have a generally straight and parallel direction 
obliquely around the egg, though their course is a regularly 
wavy one. They do not intricately cross and recross in every 
direction as in the chick’s egg, but the fibres are generally 
disposed at angles of about 45° to the principal axis of the 
egg, the direction of the obliq- 
uity alternating in successive 
layers from one side to the 
other of this axis, so that fibres 
of successive lamin are dis- 
posed at right angles to one 
another; those of alternate 
layers are parallel. The num- 
ber of laminze appears to be a 
matterof some constancy. Speci- 
mens from various parts of 
shells of three eggs were regu- 
larly separable into 9 or 10 dis- 
tinct lamine, which could be 
stripped off from the entire ex- 
? à tent of pieces an inch square 
Head of Foetal Pityophis. without exhibiting any signs of 
: thinning out. I regard them, 
therefore, as being continuous over the entire shell. These 
layers are separable from one another with great ease, but it is 
noticeable in stripping them apart that a few fibres from one 
layer are always adherent to the adjacent layers, although there 
appears to be no extensive invasion of one layer by the fibres 
of another, except among the external ones. In any one 
lamina the sinuous course of the fibres causes a firm felting 
and interlocking among them (Figs. 5 and 6). The alterna- 
tion of the direction of the fibres is shown in vertical section, 
but not very elearly, owing to the wavy courses which they 
take (Fig. 3). 
The optical effects resulting from this structure are striking 
and peculiar when the entire series of separated layers are 
S Ay 
