PROTOZOA OR SIMPLEST ANIMALS. 



17 



(Plate X. in thu Case) has a flat triangular body with a spine at each High Wall 

 angle. The two grooves form an inverted T-shape, the vertical bar ^ase 

 being very broad. The presence of cilia in the transverse band in Gallery. 

 Plate X. is incorrect, there being simply a single fiagellum lying in 

 the groove. 



Ceratium is phosphorescent, and in the open ocean is often united 

 into chains of two to twenty individuals. 



Noctiluca miliar is (Fig. 12) is a little peach-shaped organism 

 about -^^ of an inch in diameter. A thick transversely-striated 

 " big flagellum " springs from the bottom of a deep groove on one 



Fig. 13. 



VorticeUd nebulifera, a colonial Bell-Animalcule. 

 (Magnified), c v, contractile vacuole. 



side of the body. Near the groove is the mouth leading into a 

 cylindrical throat, in which is placed a second and smaller flagellum. 

 The body is invested by a firm cuticle, and the protoplasm in the 

 interior is vacuolated. See Plate XI. in the Case. 



Noctiluca is highly phosphorescent, the light emanating chiefly 

 from the protoplasm just beneath the cuticle. 



Marine phosphorescence is sometimes due entirely to the presence 

 of myriads of Noctilucce, which may be present in such abundance 



C 



