was also
fortified in this way, while the "secondsystem" was applied to Belgrade
and Temesvar in eastern Europe.

His son, Gosewijn Theodor van Coehoorn, wrote his life (re-edited
Syperstein, Leeuwarden, 1860). See also v. Zastrow, _Geschichte der
bestandigen Befestigung_ (Leipzig, 1828); von Brese-Winiari, _Uber
Entstehen und Wesen der neueren Befestigungsmethode_ (1844); Cosseran
de Villenoisy, _Essai historique sur la fortification_ (1869); Mandar,
_Architecture des forteresses_ (1801); Krayenhoff, _Verhandeling over
de erste versterkingsmanier van Coehoorn_ (Hague, 1823); Bosscha,
_Nederlandsche heldend te Land_ (Amsterdam, 1838); Dewez, _Histoire de
Belgique_ (Brussels, 1823); Ypey, _Narratio de rebus gestis Mennonis
Cohorni_ (1771); Hennert, _Dissertation sur la fortification
permanente_ (1795); Bohms, _Grundliche Anleitung zur Kriegsbaukunst_
(1776); _Axiomatas of allgemeene bekentnisse over de Vestinghbouw door
Menno Baron van Coehoorn, Uytgewerkt door E. W. Berg_ (MS. in Dutch
Ministry of War); Bousmard, _Essai general de fortification_ (1797);
also the article FORTIFICATION AND SIEGECRAFT.

COELENTERA, a group or grade of the animal kingdom, the zoological
importance of which has risen considerably since the time (1887) of the
publication of the first article under that heading in the _Ency. Brit._
(9th edit.), even though their numbers have been reduced by the
elevation of the Sponges or Porifera to the rank of an independent
Phylum under the title Parazoa (W. J. Sollas, 1884). For the Coelentera
thus restricted, the term Enterocoela, in contrast to Coelomocoela (the
old Coelomata), was suggested by E. R. Lankester (1900).

From the more complex colonial Protozoa the Coelentera are readily
separated by their possession of two distinct sets of cells, with
diverse functions, arranged in two definite layers,--a condition found
in no Protozoan. The old criterion by which they and other Metazoa were
once distinguished from Protozoa, namely, the differentiation of large
and small sexual cells from each other and from the remaining cells of
the body, has been broken down by the discovery of numerous cases of
such differentiation among Protozoa. The Coelentera, as contrasted with
other Metazoa (but not Parazoa), consist of two layers of cells only, an
outer layer or ectoderm, an inner layer or endoderm. They have hence
been described as Diploblastica. In the remaining Metazoa cer