94 OTHER CCELENTERATES 



OTHER CCELENTERATES 



Exercise 1. — ^Various Species. 



(a) With the exception of the hydras, which are common forms, 

 and a few other related species that have a very restricted distribution, 

 the ccelenterates are exclusively marine animals. Familiar examples 

 at the seashore are the jellyfishes and sea-anemones. The table of clas- 

 sification on p. 170 gives the several classes of the phylum. It will be 

 interesting to examine such museum specimens as may be available, 

 although even the best of preserved material gives a sorry picture of 

 the beauties of form and color seen in many ccelenterates when alive. 

 (1) Among the Hydrozoa, various hydroids and Physalia, the "Portu- 

 guese man-of-war," may be shown. (2) The Scyphozoa include the 

 larger jellyfishes which are somewhat different in structure and life- 

 cycle from the hydrozoan jellyfish Gonionemus. Aurelia, Cyanea, 

 and Dactylometra are common genera along the North Atlantic Coast. 

 (3) In the Anthozoa, various anemones, such as Metridium; sea-pens 

 and sea-fans; expanded specimens of the coral Astrangia attached to 

 its skeleton; and dry skeletons of various corals may be examined. 

 Where skeletons alone are available, they should be compared with 

 figures of the living animals. In any case, charts or the figures in 

 a textbook should be consulted. (4) The Ctenophora, or sea-walnuts, 

 are less abundant forms and so difficult to preserve that good figures 

 are more likely to be intelligible. 



