34 THE SUB-KINGDOM PROTOZOA. 



between one and many of these orders. The inadequacy of the several 

 systems hitherto proposed for the fulfilment of these last-named require- 

 ments, as also an outline of one closely corresponding with that here 

 introduced, were respectively recognized and provided for by the author 

 in association with the paper entitled ' A Monograph of the Gymnozoidal 

 Discostomatous Flagellata, with a Proposed New Scheme of Classification 

 of the Protozoa/ communicated to the Linnaean Society on the 2ist of 

 June, 1877, and referred to at some length in the 'Annals and Magazine of 

 Natural History' for January 1878.* In accordance with the scheme then 

 proposed, and as now submitted in its more extended form with certain 

 amendments, the fundamental basis upon which the subdivision of the 

 Protozoa into primary groups or sections is founded, bears relation not so 

 much to the varied character of the locomotive or prehensile appendages 

 possessed by the representatives of this sub-kingdom as to the nature of 

 the oral apparatus or systems subordinated to the function of food- 

 ingestion. Comparing small things with great, this morphological element 

 yields indeed as convenient and sound a basis for taxinomical diagnosis as 

 is afforded by the oral systems of the higher Invertebrata or the dental 

 formulae of the mammalian class. 



Following out this newly proposed plan of subdivision, it will be found 

 that the entire series of the sub-kingdom Protozoa range themselves into 

 four natural and readily distinguished groups or sections. In the first, 

 most lowly organized, and with reference to its subordinate subdivisions or 

 orders most numerically abundant of these several groups, an oral orifice 

 in the literal sense of the term has no existence, food being incepted 

 indifferently at any point of the periphery or general surface of the body. 

 This most simple or elementary type of structure of the Protozoa is best 

 illustrated by such familiar examples as A mceba and Actinophrys, the various 

 representatives of the Foraminifera, and certain Flagellata such as Spumella 

 and Anthophysa. For the distinction of these most simply organized forms, 

 characterized by the indefinite or generally diffused character of their oral 

 or introceptive area, the divisional title of the PANTOSTOMATA is here 

 adopted in place of that of the Holostomata originally proposed in the 

 earlier communications by the present author as above mentioned. This 

 latter term, while scarcely conveying the sense intended, possesses the 

 disadvantage of having been previously employed for the distinction of a 

 group of the Mollusca. Next in the ascending scale a group of the 

 Protozoa is met with, in which though differentiation has not proceeded 

 so far as to arrive at the constitution of a distinct oral aperture, the 

 inception of food-substances is limited to a discoidal area occupying the 

 anterior extremity of the body, and is associated with the special food- 

 arresting apparatus described in detail later on. To this section of the 

 Protozoa are naturally relegated all the minute collar-bearing flagellate 

 animalcules first discovered by Professor H. James-Clark, of which so 



* Mr. Saville Kent, " Observations upon Professor Ernst Haeckel's Group of the Physemaria 

 and on the Affinities of the Sponges." 



