'V ZOOLOGY. 571 



cerpts were indicated by quotation marks. Some misapprehension was 

 evidently entertained, as the classification really given by Mr. Kent is 

 quite different from wbat would be supposed from the original notice. 

 The Infusorians of Kent are accepted with nearly the same limits as were 

 accorded to them by Pritchard, and are essentially those Protozoans 

 which for some time have enjoyed the name, including the mouthed 

 forms and certain others evidently related to them, though dectituteof 

 the "mouth." The sponges are, however, also included in the group, 

 although the best theoretical naturalists now regard them as the most 

 generalized of metazoic animals, and thus diflerentiated as representa- 

 tives of a series contrasting with the Protozoans. Three classes are ad- 

 mitted by Mr. Kent for the Infusorians, and are designated by him 

 Flagellata, Ciliata, and Tentaculifera. These three classes include about 

 900 species, representing about 300 genera. 



Mr. Kent's work, so far as the details are concerned, will prove invalu- 

 able to the student of the low forms described. It is not at all likely, 

 however, that his philosophical conclusions will be generally accepted 

 soon, or that they will stand the test of time. Some of the principal 

 types of the animal kingdom are supposed to be genetically derivable 

 from special types of Infusorians j for example, the Annelids from the 

 Holotrichous (or Peritrichous) Ciliates, the Echinoderms, Polyzoaus, and 

 Mollusks from the Peritrichous Ciliates, the Eotifers and Arthropods from 

 the Hjpotrichous Ciliates; and the Coelenterates from the Tentaculifers. 

 In other words, the complexities of the metazoic organism must have 

 been many times independently attained from unicellular organisms, 

 and the associations or colonies of cells known as metazoic animals must 

 be supposed to repeat, as a whole, unessential features of protozoic ani- 

 malcules. Doubtless many biologists will object to such conclusions. 



Families of Flagellates. 



The Flagellata have been extended by Mr. Kent to include not only 

 the Mastigamcebidfe, the Euchitonidse, and the Noctilucidce, but also 

 the Sponges, and quite subordinate rank is given to the Koctilucidae 

 (treated as a simple family of the Eustomata), although many natural- 

 ists regard the type as of class value and more differentiated than most 

 of the Flagellates are from each other. The Flagellates thus reconsti- 

 tuted are distributed among seven orders and thirty-nine families, not 

 counting the Sponges, which are omitted from the work. The classifi- 

 cation is as follows : 



Order 1. Tryanosomata, with 1 family — the Trypanosomatidae. 



Order 2. Ehizoflagellata, with 1 family, Mastigamoebidre. 



Orders. Eadioflngellata, with 2 families : (1.) Actinomonadidai and 

 (2.) Euchitonidse. 



Order 4. Pantostomata, with 18 families: (1.) Monadidae; (2.) Pleu- 

 romonadidse ; (3.) Cercomonadidae ; (4.) Codonoecidse ; (5.) Dendrom- 

 onadidse; (6.) Bikoecidae; (7.) Amphimonadidae; (8.) Spongomonadidaej 



