The works of Francis Maitland Balfour, Volume 2 (of 4)

by Francis M. Balfour

[216] This is stated to be the case in Moina (Grobben).

CHAPTER XX.

ECHINODERMATA[217].

The development of the Echinodermata naturally falls into two sections:—

(1) The development of the germinal layers and of the systems of organs; (2) the development of the larval appendages and the metamorphosis.

The Development of the Germinal Layers and of the Systems of Organs.

The development of the systems of organs presents no very important variations within the limits of the group.

Holothuroidea. The Holothurians have been most fully studied (Selenka, No. [563]), and may be conveniently taken as type.

The segmentation is nearly regular, though towards its close, and in some instances still earlier, a difference becomes apparent between the upper and the lower poles.