CPJ AFTER I. 



STRUCTURE OF THE MEDUSA 



To give a full account of the morphology, develop- 

 ment, and classification of the MedusiB would be 

 both unnecessary for our present purposes and 

 impracticable within the space which is allotted to 

 the present work.* But, for the sake of clearness 

 in what follows, I shall begin by briefly describing 

 such features in the anatomy of the jelly-fish as 

 will afterwards be found especially to concern us. 



In size, the different species of Medusa? vary 

 from that of a small pea to that of a large umbrella 

 having streamers a hundred feet long. The 

 general form of these animals varies in 

 different species from that of a thimble 

 (Fig. 1) to that of a bowl, a parasol, or 

 a saucer (see figures in subsequent chap- 

 ters). Or we may say that the form of 

 the animals always resembles that of 

 a mushroom, and that the resemblance 



* Those who may desire to read an excellent epitome of our 

 most recent knowledge on these subjects, may refer to Professor 

 E. Ray Lankestei's article in the '* Encyclopaedia Britauuica " on 

 '* Hydrozoa," together with Professor Haeckel's Report on the 

 Medusae of the ChaZlenger Expedition. 



