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CRITICAL NOTES ON SOME SPECIES OF CERA8TIUM. 

 Bx Frederic N. Williams, F.L.S. 



A MONOGRAPH of the genus Cerastium was published by Charles 

 Grenier in 1841. In this interesting example of Grenier's systematic 

 woik, which consists of ninety-five pages, with nine plates in which 

 fourteen species are figured, forty- eight species are described. The 

 critical acumen which he showed in gauging the relative importance 

 of specific characters is exemplified in his treatment of the genus ; 

 and in a decade in which George Bentham and Jacques Gay repre- 

 sented divergent schools of systematic botanists the mild protest 

 which, in the preface to his work, he addressed to those who 

 encouraged the unnecessary multiplication of species is much to 

 the point, and will well bear repeating at the present time, which 

 has seen the completion of a lithographed presentment of the 

 Flora of Europe elaborated in twenty-seven volumes with the 

 slenderest padding of descriptive detail. Translated, it reads thus : — 

 "According as the bias of synthesis or analysis predominates in the 

 minds of those who are concerned in the study of the fixation of 

 species, you will find their number diminish or increase with the 

 examination of material. From this proceeds two schools, of which 

 one seems to be bent on the multiplication of species, whilst the 

 other, urged by the contrary tendency, seeks to restrict the number. 

 In observing what goes on around us among certain species of 

 animals and plants, in reflecting on the numerous modifications 

 which domestication, climate, the action of the sun, etc., have on 

 species; I have considered that it would be better to err by excess of 

 reduction than of multiplication, persuaded, moreover, that in doing 

 so, one would burden science less, and that there would never fail 

 men who have an opposite tendency to mine. I have always tried 

 to distinguish carefully the forms known to me ; and if in this 

 memoir of mine they are not described as species, they will be 

 found under varieties, so that others, if they have sufficient reason, 

 may raise them to the rank of species." 



It will be some considerable time before the materials for a 

 revision of the species of Cerastium can be digested and codified ; 

 and meanwhile I offer a few notes on some of the published species, 

 taking the names in strictly alphabetical order, and in collation with 

 the list given in Mr. B. D. Jackson's Index Keivensis. As Mr. J. G. 

 Baker implied in his review of Richter's Plantce EuropecB, the diffi- 

 culty in the grouping of forms lies not so much in the examination 

 and comparison of available material in the shape of specimens, as 

 in the unconscionable amount of overlapping in the more or less 

 detailed descriptions of subordinate forms under specific names 

 associated with the ever more involved and intricate tangle of 

 synonyms ; which makes neither for lucidity of sequence, nor for 

 the adequate expression of deviations from the type within the 

 limits of the genus, by the aid of a Iniear and dichotomous arrange- 

 ment. In other words, the more completely the comparison of 

 specimens is lixiviated from the bibliography of the species, the 

 simpler will be the treatment of the genus. 



