84 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



defined differential characters, but without sensibly altering their respective 

 contents. Thus, the type species belonging to the two older genera became 

 in each case the typical species of the newly proposed genera. In other words, 

 a valid generic distinction was recognized between two groups of fossil species 

 for each of which a definite type was selected ; and in each case the definite type 

 so selected was identical with the type of a previously described genus. By this 

 process of emendation and redefinition, the integrity of the older generic terms 

 was not, and, according to ordinary rules of nomenclature, could not have been 

 impaired. The genus Champsodelphis Gervais, typified by C macrogenius 

 (Laurill.) (=C macrognathus Brandt), and represented by a number of other 

 species as well, might be restricted, enlarged or otherwise modified, even broken 

 up into several genera ; but in the latter case the name Champsodelphis must be 

 retained to designate that section which contains the original type of the genus. 

 Similarly, in the case of Schizodelphis, so long as the typical species S. sulcatus 

 Gervais is not proved to belong to any previously described genus, the original 

 generic title must be retained, and no new one can be substituted in place of it. 

 Therefore it becomes necessary to regard Abel's proposed title of Cyrtodelphis, 

 having S. sulcatus Gervais for its type, as a synonym pure and simple of the 

 older Schizodelphis, which has the same type species. In the case of Cham- 

 sodelphis, Abel has himself rectified his error of 1899 by restoring this name 

 to good and regular stauding. He restricts it in his Brussels memoir of 1905 so 

 as to include only the type species, and employs the name Acrodelphis l as a 

 collective designation for the nine or ten other species formerly embraced under 

 Champsodelphis. 



Some confusion exists as to exactly what constitutes the type species of 

 Champsodelphis. Trouessart, in the quinquennial supplement, 1905, to his 

 " Catalogus Mammalium," correctly indicates G. macrogenius (Laurill.) as the type. 

 Abel, in his memoir published the same year, gives it as C. macrognathus Brandt. 

 Both names refer to precisely the same thing. The extent of Brandt's changes 

 was merely to restrict the application of Laurillard's title to the original of 

 Cuvier's " Dauphin a longue symphyse de la machoire inferieure, deterre dans 

 une sabliere du departement des Landes," and to found a new species, C. 

 valenciemiesi, upon a second specimen that Laurillard (and following him, 

 Gervais) had associated with the type. Subsequently it was pointed out by 

 Abel that the so-called C valenciennesi of Brandt bore sufficient resemblance to 

 Tursiops as to warrant its exclusion from Platanistids altogether. But instead 

 of retaining Laurillard's well-founded specific name for Cuvier's original, he 



1 As pointed out by M. Trouessart (Revue Critique de Paleozoologie, 1906, 10, 

 p. 205), the genotype of Acrodelphis is A. letochae (Brandt). "Contrairement aux 

 usages," continues this author, " M. Abel donne comme ' types ' de ce genre trois 

 especes (A. Letochae, A. Ombonii, A. denticulatus). II veut dire, sans doute, que ces 

 trois especes sont typiques." A discussion of methods of fixing the types of gen- 

 era was introduced by Witmer Stone, in Science, 1906, 24, p. 560, and continued 

 by various other systematists. 



