HYDROIDA.

Sertularia Rosea.  Pl. I. fig. 6.

A species which has the cells in pairs on opposite sides of the central tube, with the openings turned outwards.  In the more enlarged figure is seen a septum across the inner part of each cell which forms the base upon which the polype rests. Fig. 6 b indicates the natural size of the piece of branch represented; but it must be remembered that this is only a small portion of the bushy shrub.