Careful observations have been made by Repiachoff (No. 318) on the early development of Tendra, which accord in some respects with the results arrived at by Barrois in his second memoir. The observations are not, unfortunately, carried down to the complete development of the larva. The ovum divides in the normal way into two and then four uniform segments. These four next become divided by an equatorial furrow into four dorsal and four ventral segments, the former constituting the aboral pole and forming the epiblast, and the latter the oral pole. The stages with sixteen and thirty-two cells appear to be formed in the same manner as in Alcyonidium--but between the two layers of cells forming the oral and aboral poles a well-marked segmentation cavity arises at the stage with sixteen segments. At the stage with thirty-two cells the four middle cells of the oral side, which are larger than the others, become divided into two tiers, in such a manner as to form a prominence projecting into the segmentation cavity. By the appearance of a lumen in this prominence it becomes converted into an archenteron, which communicates with the exterior by a blastopore in the middle of the oral surface. The blastopore becomes eventually closed. The archenteric sack of Repiachoff is clearly the same structure as Barrois' four invaginated cells of the oral face, their further history has unfortunately not been followed out by Repiachoff. The free larva swims about for some time, and then fixes itself and undergoes a metamorphosis; but the exact course of this metamorphosis is still very imperfectly known. According to the latest statements of Barrois the attachment takes place by the oral face[124]. The ciliated disc, which in the free larva forms a kind of cup directed towards the aboral end, turns in upon itself towards the oral face. It subsequently undergoes degeneration and forms a nutritive or yolk-mass. The skin of the larva after these changes gives rise to the ectocyst or cell of the future polype. The future polype itself appears to originate, in part at any rate, from the so-called dorsal organ[125]. [124] Barrois himself held the opposite view in his earlier memoir, and other observers have done the same. [125] The statements on this head are so unsatisfactory and contradictory that it does not appear to me worth while quoting them here; even the latest accounts of Barrois, which entirely contradict his early statements, can hardly be regarded as satisfactory.