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, n, 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- 

 wig, is discoidal or medusiform in 



Tig.23.Acinetamys/,acina, , ,. -. . . . .... 



with it* stalk attached to a shape, the disk one and a half m im- 

 plant ; with fifteen tentacles . , . Tir , , . , , 



ending in knob-like expan- metres in diameter. When disturbed 

 SiEte?" U( IC ~ 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 Heteromastix and Dys- 

 teria, connecting the Flagellata with the Ciliata or true 

 Infusoria. 



Order 2. Tentaculifera (Acinetse, Suctoria). An Acinetcc 

 (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- 



