936 



SCIENCE 



[X. S. Vol. XXIX. No. 754 



the history of nomenclature ; in other words, as 

 off-hand opinions as to what seemingly ought 

 to be, regardless of the actualities of the case. 



Nomenclature (both zoological and botan- 

 ical) has attained its present stage of compar- 

 ative orderliness by slow stages of develop- 

 ment. For the first seventy years of its his- 

 tory such a concept as a " genotype " appears 

 to have been rarely, if ever, thought of; and 

 it was not until the first quarter of the nine- 

 teenth century had passed that types of genera 

 began to be considered as a necessary part of 

 the proper basis of a genus. Prior to 1810 

 hundreds of genera now in current use were 

 proposed solely on the basis of a diagnosis; 

 although they were accepted and have been in 

 use from the date of their proposal, many of 

 them were without designated types for half a 

 century. Yet the authors of this early period 

 were in substantial agreement as to what 

 groups of species these generic names were 

 intended to include. From the modern view- 

 point these genera were (usually) heterogene- 

 ous groups, each comprising several modern 

 genera. In the process of division a type was 

 sooner or later, by restriction or by actual 

 designation, assigned to the original genus. 

 Not till then did the genus, from the modern 

 vievTpoint, become properly established. Many 

 other genera of this early period, similarly 

 proposed, are unidentifiable. I can not agree 

 that these two categories should have the same 

 treatment. Nor can I agree that a long-ac- 

 cepted genus must date from the author who, 

 long after it was originally founded, "vali- 

 dated" it by designating a type for it; but 

 rather, as indicated in the first part of this 

 communication, that the genus should date 

 from its founder. Otherwise nearly all of the 

 early genera for birds would date from about 

 1840, after many of them had been in general 

 use for one half to three fourths of a century. 

 In the case of mammals, many of the early 

 genera were not thus " validated " till many 

 years later than those of birds. To take 

 genera from the date of " validation " would 

 obviously establish a new source of trouble 

 in relation to priority of names. 



It is now the custom of a large number of 

 nomenclators to make a distinction between a 



nomen nudum and a name that is for any 

 reason unidentifiable;* the former can be em- 

 ployed by a later author, from whom it 

 must date; the latter can not be again used, 

 the attempt at a diagnosis, however brief or 

 inadequate, precluding its subsequent employ- 

 ment. Hence a name founded on a diagnosis, 

 and subsequently validated, can not be taken 

 from the validating author, but must date 

 from the founder, if this rule be followed. 

 Furthermore, to call a genus a nomen nudum 

 when based on a diagnosis is a misuse of lan- 

 guage, and entirely contrary to usage. 



J. A. Allen 

 Amebican Museum or Natural History, 

 New York 



the origin op the moon 

 In his inaugural lecture delivered in Co- 

 lumbia University, November 3, 1908,' Dr. 

 Albrecht F. K. Penck, the Kaiser Wilhelm 

 " Umtausch " Professor, spoke in part as fol- 

 lows concerning the geographical and geo- 

 logical similarities between the eastern coast 

 of North America and the western coast of 

 Europe : 



These similarities between Europe and penin- 

 sular North America are not merely superficial 

 ones. In a very remarkable way, these Uvo sides 

 of the Atlantic repeat the same structural fea- 

 tures; there is an astonishing symmetry, as 

 Eduard Suess has shown so clearly. The north- 

 east of Canada and Labrador on one side, and 

 Scandinavia with Finland, the region of Feno- 

 Scandia, on the other, are both composed of the 

 oldest rocks we know of. These have a very com- 

 plicated structure, being intruded with many 

 eruptive rocks, and in a secondary way only, the 

 surface features of the above regions are de- 

 pendent on their structure. Both regions had 

 already been leveled down before Cambrian times, 

 and they sink gently down under a cover of hori- 

 zontal Paleozoic strata. Both were called by 

 Suess shields. The resemblance between these 

 shields is the more conspicuous because both were 

 covered during the last ice age by a glaciation 

 which molded their surface in a similar way. In 

 Sweden and Finland we find the same rounded 



'See Revised A. 0. U. Code, Canon XXXIV., 

 and the explanatory " remarks." 



' For the whole lecture see Science, February 

 26, 1909. 



