Analysis.

Of ten holothurians about whose development we have any knowledge, only three form Auriculariae. The other seven species all have large yolky eggs and a more or less direct development. Two of these are known to have the special simplified “yolk-larva” which I have termed “Vitellaria” (see a later section of this paper) and the remainder may have absolutely direct devlopment.

Of the two crinoids whose development is known, both have large yolky eggs, and both form the same yolk-larva or Vitellaria.

Among the asteroids, only seven out of nineteen species have a pelagic development. The remaining twelve species all have large yolky eggs and probably direct development to a greater or less extent. In this class there is as yet no evidence of the existence of the “Vitellaria” larva.

In the ophiuroids, of the sixteen species about which there is any evidence, four have direct development as a result of viviparity or large yolky eggs. Of the remaining twelve species, not all have typical plutei, and stages in the loss of the arms are to be observed. In a species of Ophiura a Vitellaria is known.

In the echinoids there is far less tendency to have direct development. However, of fourteen species about which we have any informa-