ON THE DEVELOPMENT OF LICHENOPORA VERRUCARIA. 77 
at from above, except in those individuals which stand nearly 
vertically. The cylindrical zocecium is, in fact, obliquely cut 
off in the way which has been indicated by the above com- 
parison, and this will be better understood by referring to 
fig. 6. The “nib” of the zocecium is commonly in the form 
of a single spike, but it may be split, so that two, three, or 
even more spikes occur. ‘These are very delicate structures in 
young zocecia, but they are readily broken off, or lost in other 
ways, in old zoecia. In young colonies the zocecia usually 
possess more than one spike each. At the growing margins of 
old specimens the occurrence of a single spike is much more 
common—if, indeed, it is not the rule. 
Between the more centrally placed zocecia stretches a calca- 
reous lamina (fig. 7)—the roof of the ovicell. This lamina is 
not even, but is obviously composed of a number of convex 
portions, separated from one another by shallow grooves. The 
ovicell opens to the exterior by means of a trumpet-shaped 
aperture, within whose expanded mouth is a straight edge, 
turned towards the centre of the colony. The section of the 
trumpet is at this level semicircular. The straight edge cor- 
responds to the level at which the trumpet springs from the 
roof of the ovicell. On the opposite side, however, the wall 
of the trumpet is longer, so that it becomes continuous with 
the roof of the ovicell at a somewhat lower level. Its passage 
into the roof is at the same time more gradual and less angular 
than on the side which faces the centre of the colony. 
This arrangement of the aperture of the ovicell may be 
regarded as characteristic of L. verrucaria. The straight 
edge may correspond with the valve which I have described 
(5) in the ovicell of Crisia, and its function may be to restrain 
the too rapid birth of the larve. 
The early stages in the growth of a Cyclostome colony have 
been well described by Barrois (2 and 8), and my results agree 
with his so far as the general character of the growth is con- 
cerned. It has not, however, been previously noticed that the 
study of the earliest stages of the colony is essential for the 
proper understanding of the ovicell of Lichenopora. 
