(top center): Aurelia insulinda (Haeckel) = Aurelia aurita (Linnaeus, 1758)?, medusa from below
(bottom right): Aurelia aurita (Lamarck) = Aurelia aurita (Linnaeus, 1758), polyp budding off medusae
(right): Undosa undulata (Haeckel) = Undosa undulata Haeckel, 1880, medusa, internal organs from below
(top right): Floresca parthenia (Haeckel) = Floresca parthenia Haeckel, 1880, medusa from the side
(top left): Pelagia perla (Haeckel) = Pelagia noctiluca (Forsskål, 1775), medusa from the side
(left): Pelagia perla (Haeckel) = Pelagia noctiluca (Forsskål, 1775), medusa umbrella in cross-section from above
(bottom left): Pelagia perla (Haeckel) = Pelagia noctiluca (Forsskål, 1775), rhopalium
(center): Drymonema victoria (Haeckel) = Drymonema dalmatinum Haeckel, 1880, medusa, umbrella center from above
(bottom center): Procyanea protosema (Haeckel) = Cyaneidae sp.?, juvenile, umbrella from below (bottom), umbrella from above (top)
Date 1904
Source Kunstformen der Natur (1904), plate 98: Trachomedusae (see here, here and here)
Author Ernst Haeckel (1834–1919)
Source: https://commons.wikimedia.org/wiki/File:Haeckel_Discomedusae_98.jpg

Aurelia insulinda, Aurelia aurita = Aurelia aurita
The common jellyfish, moon jellyfish, moon jelly, or saucer jelly (Aurelia aurita) is a widely studied species of the genus Aurelia. The moon jellyfish is translucent and can be recognized by its four horseshoe-shaped gonads, easily seen through the top of the bell. Aurelia aurita is found along the eastern Atlantic coast of Northern Europe and the western Atlantic coast of North America.

Undosa undulata
Poorly known jellyfish species.

Floresca parthenia
Floresca parthenia is a jellyfish species in the Ulmaridae family. Floresca parthenia was first scientifically described by Haeckel in 1880.

Pelagia perla = Pelagia noctiluca
The mauve stinger jelly (Pelagia noctiluca) is a jellyfish in the family Pelagiidae. In Latin, pelagia means "of the sea", nocti stands for night and luca means light; thus, Pelagia noctiluca can be described as a marine organism with the ability to glow in the dark.

Drymonema victoria = Drymonema dalmatinum
The pink meanie jellyfish (Drymonema dalmatinum) is a species of true jellyfish, placed in its own family, the Drymonematidae. It is found in the Atlantic Ocean and Mediterranean Sea.

Procyanea protosema
Poorly known jellyfish species.