132 THE JOVRXAL OF B0TA:>»T 



Lack of s\mce prevents the publication of the list of name- 

 changes ; if Dr. Pennell desires to see it, I shall be pleased to send 

 him a copy. 



The following examples illustrate the inHuence of the generic 

 concept on the amount of name-change required : — Mertensia (1797) 

 is a genus kept up in Britton and Ih-own, ed. 2, but is here countwl 

 as invalid under the Auxerican Code. The explanation is simple : 

 Pueumaria (17G4) is treated bv Britton as an indej^^endent monotypic 

 genus, but by Dalla Torre and Harms as congeneric with Mertensia. 

 This is a case in which generic segregation would diminish the number 

 of name-changes rec^uired under the American Code. On the other 

 hand, Digitaria Scop., non Heist., which Britton and Brown replace 

 by Syutherisuui Walt., has not been counted above, owing to the fact 

 that Dalla Torre and Harms regard it as a section of Fanicum, In 

 this instance, generic segregation would increase the number of name- 

 clianges recpiired under the Code. 



It may heme ntioned i\\xt lihinanthiisis included among the generic 

 names not on the list of "nomina conservanda " which are invalid or 

 differently a]>plied under the American Code. This is because the tyi)e 

 of Iihi)ianthu&,^'& is evident from the meaning of the generic name, is 

 li. Eleplias {Wii/nchocon/s Slephasy. and not i?. Grisfa-galli, as stated 

 b}'' Britton. But Ilht/uehocori/s is a "nomen conservandum," and hence 

 the name JRhinanthns may be used under International liules, though 

 not under the American Code, for the genus typified b}^ B. Crista-f/alli. 



An examination of Dr. Pennell's arguments shows that what he 

 has had under consideration — he has given no estimate — is the number 

 of name-changes wdiich adherents of the American Code with the 

 generic concept of Britton and Brown would have to adopt if they 

 accepted the International Rules. This is doubtless smaller than the 

 number of changes which adlierents of the International liules with 

 the generic concept of Dalla Torre and Harms would have to ado]>t 

 if they accepted the American Code. But this is surely an argument 

 in favour of accepting the International liules. 



It will be noticed that Dr. Pennell strikes out Taraxaoiim fix>m 

 the list of New England "nomina conservanda" which cause divergence 

 between the usage of the two schools. This is on the ground that it 

 is " put by Dr. Britton in Leontodon L., of which name it is the his- 

 toric api>lication." He apparently thinks that " nomina conservanda " 

 are maintained merely against the " nomina rejicienda *' cited, having 

 overlooked the significance of the words "nomina generica utique 

 conservanda " and " une liste de noms qui doivent eti-e conserves en 

 tons cas " (see Journ. Arn. Arb. ii. 158 ; 1921 : Kew Bull. 1921, 175 • 

 Journ. Bot. 1922, 52). The })resence of Turasacum on the list of 

 " nomina conservanda " precludes the use of the Bame Leontodon for 

 the genus typified by X. Tara^vaeum. 



Dr. Pennell suggests the following compromise between the Inter- 

 national liules and the American Code : — 



1. Untypified generic names (hy])onyms) to be rejected. 



2. Homon3ans, generic and specific, to be rejected., 



3. The American m^ethod of typifying genera to be accepted in 

 its o-eneral outlines. 



