PROTOZOA OR SIMPLEST ANIMALS. 
17 
(Plate X. in the 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 ^ as e e nd of 
being very broad. The presence of cilia in the transverse band in Gallery. 
Plate X. is incorrect, there being simply a single flagellum lying in 
the groove. 
Ceratium is phosphorescent, and in the open ocean is often found 
united into chains of two to twenty individuals. 
Noctiluca miliaris (Pig. 12) is a little peach-shaped organism 
about Jq of an inch in diameter. A thick transversely-striated 
“ big flagellum ” springs from the bottom of a deep groove on one. 
Fig. 13. 
Vorticella nebulifera , a colonial Bell-Animalcule. 
(Magnified.) c v, contractile vacuole. 
side of the body. Near the groove is the month 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 Noctiluca } , which may be present in such abundance 
c 
