154 Proceedings of the Royal Irish Academy. 



remarking that for nearly seventy years the authorities have agreed on one 

 point at least, viz., the difficulties attaching to any attempt to define specific 

 or even generic houndary lines. 



Nearly every student of that brancli of the subject with which we are 

 especially occupied, the bionomics, no less than theclassification, of theForamini- 

 fera, has contributed his pronouncement, which has almost invariably taken 

 the form of a warning. As long ago as 1848 Williamson in his paper upon 

 the I^ageuae observed that " extreme forms which appear to be \ ery distinct 

 from one another may be connected together by specimens of an intermediate 

 aspect to an extent only to be believed by those who examine a large series 

 of specimens side by side."^ In 1864 H. B. Brady pointed out that " in the 

 Protozoa a much larger range of variation must be allowed, within specific 

 limits, than it is usual t<i grant in more highly organized behigs "^ —an observa- 

 tion which may be read usefully side by side with E. A. Jlinchin's statement: 

 " It is certain that, with increasing knowledge, many species of Protozoa now 

 regarded as distinct will prove to be developmental stages of others, as has 

 happened so frequently in the case of the Metazoa"' — a remark to which we 

 shall refer again when we come to discuss the question of multiformity. But 

 Minchin himself became his own adrocatus diaboli when, in the same work, 

 he stated that a specific distinction lietween two things which shade off into 

 one another I>y infinite gradations is not by those gradations rendered invalid 

 any more than the gradual transition from spring to summer does away with 

 the distinction between the seasons.* 



'l"he case has been admirably summed up by J. .1. Lister as follows: — 

 " The question appears to be, not whetlier all internu'diate forms do or do not 

 exist between dissimilar forms, but whether liio whole body of forms, as they 

 occur in nature, t«nd to group themselves or are aggregated about certain 

 centre-s. . . . To refuse to recognize the existence of these centres because 

 transitional forms cxi.st between them is to ignore an essential fact. 

 In a very large number of cases, at any rate, such centres do exist among the 

 Foraminifera as among other organized beings, and the characters of the 

 viiddU individuals of them are those of the species."^ 



' W. C. Willinmioii : "On the Recent British Species of the Genus Lagena." Ann. 

 M.ig. NHt. Hist., Ser. 2. 1S48. vol. i, p. 10. 



' H. B. Brady: "On the Rhizopodal Fauna of the Shetlands." Trans. Linn. Soc, 

 vol. sxiv, 1H64, p. 464. 



^ E. A. Minchin: "Introduction to the Study of the Protozoa." London. 1012, 

 p. 164. 



* Loc. cif. , p. 07. 



'J. .1. Lister: "The Formminifera," in E. Ray Lankester's "Treatise of Zoology," 

 Ft. 1 , Fasc. 2. London. 1903. p. lU. 



