September 20, 1907] 



SCIENCE 



379 



Authors have adopted at least four methods 

 of arranging their species : (1) the technical, 

 as I will call it; (2) the biological; (3) the 

 stratigraphical, as Dr. Bather points out; (4) 

 the alphabetical. 



By the technical I mean that the author 

 describes the genotype first, and then places 

 his other species in sequence according to 

 their degree of difference from it. This is 

 the only plan to which a first species rule 

 applies justly; but this plan, though it may 

 be common in neontology, is certainly rare 

 in paleontology, where any of the other three 

 methods are more usual. 



The biological system consists in arranging 

 species according to their supposed genetic 

 sequence; but the middle or last species may 

 be the genotype as often as the first. The 

 biological plan may be stratigraphical in re- 

 sult; but not in intention. This biological 

 method was used by Hyatt. For instance in 

 his genus Tropidoceras, to name one case 

 among many, he placed three species {Bull. 

 Mils. Comp. Zool., 5, 1867, p. 93). It can be 

 seen from the method of his later works that 

 he regarded these species as forming an ana- 

 genetic series, of which the first two were the 

 immature, larval forms while the last was the 

 mature, fully developed type of the genus; 

 it conforms the best with his diagnosis. This, 

 therefore, is the one to take as his genotype; 

 a first species rule would do him injustice. 



In my genera (Mon. I. O. Amm., Suppl.) 

 the species are arranged on Hyatt's plan — in 

 supposed genetic sequence. My genotypes are 

 stated; but had they not been, the first species 

 rule would fail to interpret me correctly; my 

 genotypes come frequently in the middle of 

 the series — ^preceded by species biologically 

 less, succeeded by species biologically more, 

 developed. 



The stratigraphical method was one much 

 favored by the older paleontologists. In such 

 a work as d'Orbigny's " Prod. Pal." the whole 

 arrangement is stratigraphical; that governs 

 the first mention. Opening at random, I find 

 Crypioceras d'Orbigny first species mentioned 

 C. subtuberculatus of the Devonian; but it is 



obvious that he regarded as the genotype C. 

 dorsalis of the Carboniferous. 



In other works species may be arranged by 

 zones or beds, beginning with the earliest; 

 the first species need not be the author's type. 



Of the alphabetical method an instance may 

 be seen in M'Coys " Carb. Foss. Ireland." 

 His first species of Brachythyris is B. duplici- 

 costa. Dall in his most useful work, " Index 

 Names Brach.," records this species; and the 

 inference is that he regards it as the type. 

 But M'Coy had depicted without final name 

 a form of Brachythyrus a few pages earlier; 

 this is obviously his type and it is B. oralis 

 which comes sixth. In Martinia the first 

 species is M. decora, as Dall records; but 

 M'Coy had figured an example in the same 

 way, which is clearly a form he united under 

 M. glabra; that comes third. Then M'Coy 

 had given a further indication that he regard- 

 ed M. glaber as his type — by using Martinia, 

 for glaber is Martin's species. 



Then there are cases in which the author 

 indicates his type by making the generic name 

 resemble a trivial one. Thus the obvious type 

 of Reticularia M'Coy is B. reticulata; of 

 Fusella M'Coy, S. fusiformis; of Ornithella, 

 Deslongchamps, T. omithocephala. 



Since in these various cases where the geno- 

 type has been stated or obviously indicated 

 the first species rule is demonstrably unjust, 

 it follows that in other cases it is quite as 

 likely to be wrong. A rule which presumes 

 to interpret correctly in unknown cases must 

 surely be able to show that it does justice in 

 known cases. Tested by these the first species 

 rule breaks down. S. S. Buckman 



Thame, England, 

 August 2, 1907 



HOLOTHURIAN NAMES 



Dr. Theo. Gill, in the August 7 issue of 

 this journal (p. 185) rightly takes exception 

 to the use of Holothuria for a genus of echino- 

 derms. In my paper on " The Holothurians 

 of the Hawaiian Islands " I used the name in 

 the sense that Theel, Lampert, Ludwig and 

 every other writer in recent years has em- 

 ployed the term, and I did not, as Dr. Gill 



