INFUSORIA. 



33 



The earlier writers were in the habit of describing any flagellate, just discernible with 

 their lenses, as Monas, no matter how many flagella it possessed, hence the number of 

 so-called species of Monas is very large. Many have been put into other genera, while 

 others arS still doubtful. It was one of these, Monas daUingeri, that served for the 

 beautiful series of observations on the life-history of the monads referred to on a pre- 

 vious page. These minute creatures can be studied only by means of high powers. If, 

 after long and careful watching, a form is found, otherwise just like Monas, which does 

 not change its shape, it belongs to Stein's genus Scytomonas ; if the anterior border is 

 truncate it is Cyathomotxas ; fusiform and persistent in shape, Leptomonas ; vermicu- 

 lar and spirally twisted with form persistent, Ophidomonas ; vermicular and change- 

 able irfform, Herpetomonas ; if adherent at will by a trailing flagellum, Ancyromonas. 

 This analysis is given to show with what care these animals must be studied before they 

 can be firoperly referred to their genera. 



The remaining three families of the Monomastiga differ in having the flagella lateral, 

 or the animalcule with a tail-like filament, or enclosed in an indurated sheath, the lorica. 

 In the genus Bodo, the ovoid, or elongate, plastic bodies have a tail-like filament ; they 



rio. 26. — Five zooids of Anthophysa, enlarged 1000 times. 



Fig. 27. — Large colony of Anthopliyaa, 



are mostly parasites in the intestinal canal of animals, especially of reptiles and insects. 

 At times they abound in myriads. The encystment of £. lymncei has been recorded 

 by Ecker. On examining the opaque eggs of the pond-snail, many were found densely 

 packed with minute cysts ; these bursting, gave birth to swarms of monadiform germs. 

 The two most remarkable and beautiful genera are loricated. Codonceca costata, an 

 American saltr water form, was described by H. J. Clark: the bell-shaped lorica or case 

 stands erect on a rather long, rigid stalk ; the upper part of the cup is expanded and 

 apparently fluted. Kent has discovered another species with a smooth, ovoid lorica; it 

 inhabits pond-water. The other loricated form, Platytheca micropora, differs from the 

 preceding in lying flat upon its support like Platycola of the peritrichous Ciliata ; it is 

 found on the roots of the duck-weed. 



The first family of the Dimastiga includes singularly striking species, which, by their 

 tree-like supports, or zoodendria, may easily be mistaken for an Epistylis ; in fact, 

 more than one of the few species have been figured and described as species of the 

 genus named, but the irregular, oblique animalcules bearing two, equal, anteriorly 

 placed flagella shftuld at once determine the proper place of these forms. The writer 

 once found an Anthophysa abundant in a Jar of water in which Char a fragilis had 

 been kept for some time ; it was taken for A. vegetans. Colonies attacbed to their 

 granular, fragile stalks were seen, but the greater number were free-swimming. Figs. 



VOL. L— 3 



