34 ZOOLOGY. 
ophagus which passes into the digestive cavity, in front of 
which lies an oval nucleus. Beneath the outer skin or firm 
membrane surrounding the body is a gelatinous layer, con- 
taining numerous granules. A network of granular fibres 
arises from the granular layer ; these fibres pass into the 
middle of the body to the nucleus and digestive cavity. The 
young (Fig. 22, 7, s) result from a division or segmentation 
of the entire mass of the protoplasm of the body, forming 
small oval bodies with a long lash. The zoospores are like 
those of other Flagellata, and for this reason and the gen- 
eral structure of the adult, Noctiluca is by the best author- 
ities associated with the Flagellata. Noctiluca also under- 
goes conjugation, but the zoospores 
appear whether conjugation has oc- 
curred or not. The Noctiluca on the 
coast of the United States has been 
—. observed in abundance on the surface 
" of the sea in Portland harbor, by Mr. 
E. Bicknell. It is phosphorescent, 
but whether identical with Noctiluca 
miliaris of the European seas is not 
known. Leptodiscus medusoides Hert- 
Sk gage wig, is discoidal or medusiform in 
wih Gee cated ee em the disk one and a half milli- 
plant ; with fifteen tentacles 6 6 6 
ending in knob-like expan- metres in diameter. When disturbed 
allisters noe Prom Me it darts through the water by the con- 
tractions of its umbrella-shaped body. 
It is allied to Noctiluca and was discovered at Messina. 
Peridinium is the type of a third and higher division of 
monads, the body being protected by a hard shell, with one 
or more flagella, and a row of cilia serving as a locomotive 
apparatus, and thus, together with Heteromastiz and Dys- 
teria, connecting the Flagellata with the Ciliata or true 
Infusoria. 
Order 2. Tentaculifera (Acinete, Suctoria).—An Acineta 
(Fig. 23) reminds us at first sight of a Radiolarian, since 
the body is provided with filiform, tentacle-like processes 
resembling the pseudopodia of a Radiolarian, but the ten- 
tacles are in reality rather stiff, hollow, and act as suck- 
