OF THE PROTOZOA. DYSTERIA. 387 



termed the ^' ovaries," or the masses of brownish-red matter which sometimes 

 nearly fill the interior. Perhaps the brown granular matter which at times 

 accumulates in and about the nucleus of Noctiluca, and which is probably- 

 related to the reproductive function, is the luminous material in this ani- 

 mal ; and there is nothing contrary to analogy in supposing the development 

 of phosphorescence to be associated with a particular period of vital activity, 

 but rather everytliing in its favour. The following valuable note on the 

 collection of specimens occurs in Dr. Webb's excellent paper {op. eit. p. 102) : 

 — "As a caution to those who may undertake the further examination, I may 

 state that the buoyancy of the Noctiluca is such as to bring it to the surface 

 of tranquil water without any apparent effort, and that the best way to 

 effect its capture is, not as is most frequently done, to use the muslin net, by 

 which means the greater number of the creatui'es are lost or destroyed, but 

 to skim the top, and especially those parts near the sides of the vessel in 

 which the water has been standing. If removed in this way, and kept by 

 themselves in a test-tube, they may be preserved for two or three weeks 

 without a fresh supply of water. Even at the end of that time, if they die, 

 it does not appear to be from having reached the natural term of their ex- 

 istence, but as the result of some accidental cause ; they will not, however, 

 bear carriage to any great distance in closed vessels." 



We gather the following hints for the capture of Noctilucida from a paper 

 by Col. Baddeley {T. M. S. 1858, p. 79) -.—"Attach," he says, " a fine muslin 

 net to the end of a light pole, and proceed to some spot where the Noctilu- 

 cida are likely to be driven. A breakwater which causes an eddy to collect 

 Medusce, (fee. generally yields a good harvest. Skim the sui'face, and wash 

 the net repeatedly in a can of salt water. At night these creatures are easily 

 seen by their luminosity ; by day, if plentiful, they cover the surface of the 

 sea in brownish streaks .... The best winds in which to capture these crea- 

 tures appear to be those from south to west ; during their prevalence, I 

 have taken Noctilucce every month of the year on the east coast of England ; 

 but it is during the summer months they are most abundant, and during 

 calm weather. Abroad, they are constantly to be met with in warm lati- 

 tudes ; and I feel confident some interesting results might be obtained by 

 securing these creatures in various parts of the world." In conclusion he 

 refers to the Diatomece which are so commonly found in considerable quantities 

 in their interior. 



FAMILY III.— DYSTERIA. 

 (Plate XXXI. Figs. 24-27.) 



Dysteria, which is clearly the type of a new family of animalcules, was so 

 named by Prof. Huxley in honour of its discoverer, Mr. Dyster. Although 

 its exact systematic position and afiinity are not agreed upon, it certainly 

 occupies a position in the zoological scale above the Ciliata, if it does not 

 rightly take its place, as Mr. Gosse contends, among the Rotatoria. 



As we have unfortunately no knowledge, personally, of this interesting 

 being ; we must avail ourselves of the excellent description afforded by Prof, 

 Huxley {J. M. S. 1857, p. 78), and of the critical examination of its affinities 

 furnished by Mr. Gosse (ibi^l. p. 138). 



" Dysteria armata has an oval body, ^b^^ ^^ TOT^^ ^^ ^^ 'va.Qh. long, by 

 ji^th to -^^th broad, which is not altogether sjnnmetrical — the one side 

 presenting a considerable evenly-rounded convexity, while the other, less 

 prominent, is divided by an angulated longitudinal ridge into a smaller, 

 dorsal, and a larger, ventral area. The edges of both lateral surfaces are 



2c2 



