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 



Fi%.23.Actnetamystactna, _ ,1-1-1 -IT 



with its stalk attached to a shape, the disk one ana a halt milli- 



plant ; with fifteen tentacles . , . TT.., ., . . , , 



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



sions or puckers. From Mac- -111,1 1,1 i 11 



aiiister. 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 (Acinetae, 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- 



