. A manual of zoology. Zoology. Fig. 197. — Hahjclyslu^ anrtculiu ia.* (After Clark.) Some forms differ from the foregoing description in structure and ap parently in development. Some have only four sen- sory bodies, tiie places of the other four being taken by tentacles. In these cases the sensory organs lie (Peromedusa;) in the same radii (, interradii) as the sexual organs or (Cubomedusae) the sense organs are perradial. Lastly, some have no sensory organs, their place being either taken by tentacles oi' left vacant (Stauromedusse). This sliovrs that tenta- cles can replace sensory ped
. A manual of zoology. Zoology. Fig. 197. — Hahjclyslu^ anrtculiu ia.* (After Clark.) Some forms differ from the foregoing description in structure and ap parently in development. Some have only four sen- sory bodies, tiie places of the other four being taken by tentacles. In these cases the sensory organs lie (Peromedusa;) in the same radii (, interradii) as the sexual organs or (Cubomedusae) the sense organs are perradial. Lastly, some have no sensory organs, their place being either taken by tentacles oi' left vacant (Stauromedusse). This sliovrs that tenta- cles can replace sensory pedicels, and since they have essentially the same structure, they, like the oordylii of the Trachymedusse, are modified tentacles. Order I. Stauromedusae (Calycozoa). The best known forms are the Lucernarias (fig. 198), whose extimbrellar surface is drawn out into a stalk by which the animals ai'e attached. The disc is drawn out into eight lobes, each with a cluster of knobbed tentacles. Several species, dark green in color, occur in New England waters. The Tesseridce (unknown in America) are free-swimming. Order II. Peromedusse. Cup-shaped medusae with four i)iterradial sense bodies. Mostly high sea forms. Pencolpa, Peiip/iyl/a in the Gulf Stream. Order III. Cubomedusae. Sense organs perradial in position. Occurring in tropical and semi- tropical seas. Charijhdea (fig. 198). Development unknown. Order IV. Discomedusse. These are the most abundant and richest in spe- cies of Scyphomednsse and hence have served as the basis of the foregoing account. The order is subdi- vided according to the characters of the mouth. (1) , mouth triangular without oral tentacles; .shape and other features of the ephyra retained in the adult. Nausithoe alhida (fig. 86) of Europe is noticeable because its scyphopolyp, de- scribed as Stephanocjjphus inirabih's, is parasitic in sponges. Liiienjes and Atnlla in the Gulf Stream. (2) , mouth X-shapod with long fringed and folded a
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