74 SIDNEY F. HARMER. 
a series of ridges whose cross section has the form of MM. The 
iichenopora is then mounted (dry) on the slopes of the 
ridges ; and this allows of the examination of one edge of the 
colony. An improvement on this method, whereby each 
colony could be examined in a series of positions, was effected 
by taking a short length (about 18 mm.) of brass tubing, 
through the axis of which a long needle was passed, the 
interval between the needle and the tubing being then filled 
up with sealing-wax. The outer surface of the brass was 
covered with black paper, on which numerous colonies were 
mounted. The needle, to which a suitable head is attached, 
serves as an axis permitting the revolution of the brass cylinder 
under the microscope. 
The largest colony, among my preparations, has a maximum 
diameter of 5°47 mm. ‘The older colonies are invariably 
altered in appearance by the occurrence of secondary thicken- 
ings of the surface. 
Literature.—A large number of descriptions and figures 
of the ovicells of Cyclostomata are scattered through the litera- 
ture of the Polyzoa, and some of these are alluded to below. 
The only paper which needs special notice here is the second 
of Smitt’s admirable series of memoirs dealing with the Scan- 
dinavian Polyzoa (20). Smitt has thoroughly understood the 
general growth of the colony, and to a large extent that of the 
ovicell of L. verrucaria, the particular species we are con- 
sidering. But as Smitt was not concerned with the embryonic 
development, he paid no attention to the earliest processes in 
the formation of the ovicell. As, moreover, I cannot agree 
with all the statements of this observer, a complete account of 
the development of the entire colony must be given. In further 
justification of this course, I may mention that although it is 
perfectly obvious to any one who has made an independent 
study of L. verrucaria that Smitt had grasped many of the 
important facts, the figures which he has given are insufficient 
to explain his meaning to anyone who is not well acquainted 
with the species. 
