224 



CCELENTERATA 



Order II. Stauromedusae. 



Best known are the LUCERNARLE (fig. 189) which lack marginal bodies, but 

 usually have four small tentacles in their place, while the adradial regions are 

 drawn out into arms, bearing bundles of tentacles. The aboral surface of the 

 bell is produced into a stalk by which the animals are attached. The TESSE- 

 RUXE (unknown in America) are free-swimming. 



Order III. Peromedusae. 



Free-swimming, cup-shaped medusae, with four interradial sense bodies; 

 mostly from the high seas. Pericolpa, Periphylla in Gulf Stream. 



Order IV. Cubomedusae. 



Differ in the four perradial sense bodies, 

 ment unknown. Charybdea (fig. 190). 



Tropical and subtropical; develop- 



FIG. 189.- Halyclystus auricularia* 

 (after Clark). 



FIG. rgo. Char \bdea marsiipialis 

 (from Hatschek). 



Order V. Coronata. 



A coronal furrow on the exumbrella; four to sixteen marginal sense bodies as 

 in Discomedusae, but eight gonads and presence of cathamma. Some of these 

 formerly regarded as Discomedusae (under the name of Cannostomeas), because 

 of eight sense bodies. Nausithoe albida arises by terminal budding from a 

 scyphostoma (Stephanoscyphus mirabilis) parasitic in sponges. Atolla. 



Class III. Anthozoa (Actinozoa). 



The Actinozoa, including the sea anemones, sea pens, and corals, 

 are exclusively marine. With few exceptions they are sessile and usually 

 form colonies, often of enormous size. In this as in appearance (fig. 192) 



