The =Rhizostomæ=, or root-mouth jellyfishes, are very remarkable. They have no tentacles, but covering the end of the manubrium and hanging from it like tentacles are oval appendages with numerous minute funnel-like apertures, called suctorial mouths. As the manner of locomotion of jellyfishes is peculiar to themselves, so also is this many-mouthed development unique in the animal kingdom. The type of this group, described below, is found on the Florida Keys. The different species vary in diameter from three to eight inches. [pg140] GENUS ^Cassiopeia^ [Illustration: /Pelagia cyanella./] ^C. frondosa.^ This species has a circular disk, on the margin of which are sixteen sense-organs (tentaculocysts), but no tentacles. The lower end of the manubrium, which in other jellyfishes is an open mouth, is closed by eight arms which emanate from it and are usually extended laterally, lying parallel to the disk. These arms are much branched, and the branches, in turn, have numerous appendages. Some of these appendages look like little polyps and have mouths surrounded by crowns of tentacles; others are ovoid bodies without external openings, but with a central cavity connected with vessels leading to the arms. The former are mouths, but the function of the ovoid bodies is not known. Although able to swim freely, /Cassiopeia/ lies usually on its back, as if attached, and languidly opens and closes its disk, rarely changing its position. Its arms, extending upward, appear like the fronds of algæ. These jellyfishes are common on the Florida coast, huddled together on the sands of the coral reefs. (Plate XLIV.) [pg141] TABLE SHOWING THE CLASSIFICATION OF THE ACTINOZOA DESCRIBED IN THIS CHAPTER Class =ACTINOZOA= Subclass =Zoantharia= (/Mesenteries numerous, usually in multiples of six; tentacles unbranched hollow cones/) Order =ACTINIARIA= (/The sea-anemones. Single; no skeleton/) Genera Species ^Metridium^ ^M. marginatum^ ^Rhodactinia^ ^R. davidsii^ ^Holocampa^ ^H. producta^ ^Sagartia^ ^S. leucolena^ Order =MADREPORARIA= (/The stone- or reef-corals. Colonies; skeleton calcareous/) ^Oculina^ ^Astræa^ ^Meandrina^ ^Diploria^ ^D. cerebriformis^ ^Madrepora^ ^M. cervicornis^ ^M. palmata^ ^Astrangia^ ^A. danaë^ Order =ANTIPATHARIA= (/The black corals/) Subclass =Alcyonaria or Halcyonoida= (/Tentacles and mesenteries eight in number; tentacles feathered, that is, with uniform branches/) Order =ALCYONACEA= ^Alcyonium^ ^A. palmatum^ ^Tubipora^ Order =GORGONACEA= (/The sea-fans and sea-whips. Compound, tree-like colonies, with horny axis, branching throughout/)