thicker than the others, which in life is whipped 

 about in the water, thus functioning as a propeller 

 or oar. Among the Dinoflagellata none bears a 

 popular name; but for the benefit of the curious, 

 I will give the one that science has devised for this 

 particular form, Polykrikos schwarzi — a mongrel 

 mouthful meaning "many rings." A more musical 

 term, however, is Ceratium reticulatum, which 

 graces another individual near-by; but except for 

 the sameness of its surface texture, it would never 

 be suspected by the amateur microscopist as one of 

 the crowd. In keeping with its title it is truly a 

 "horned network." It is a rounded, basket-like 

 affair having on opposite sides at the rim a pair of 

 great horns, somewhat curved, bearing a resem- 

 blance to those of a bull. A third horn, greater 

 still, projects straight from the bottom of the 

 basket. And now, situated almost in the center of 

 the slide, comes Noctiluca; easily the simplest in 

 form, if not the greatest in size, of all the three 

 hundred or more different Dinoflagellata that 

 dwell in the so-called seven seas. 



It is due chiefly to certain species of Dinoflagel- 

 lata that the sea not only becomes phosphorescent 

 at night, but also oftentimes assumes a deep and 



[11.5] 



