2 THE PLAGIOSTOMIA. 



which various references are made below may be cited: — the " Dictionnaire 

 raisonne" universel d'histoire naturelle" by Valmont de Bomare, Paris, 1765, 

 republished in several editions (the second, 1768, a four volume quarto being 

 used here), and the "Neuer schauplatz der natur nach den richtigsten beobach- 

 tungen und versuchen in alphabetischer ordnung durch eine gesellschaft von 

 gelehrten," Leipzig, 1775-1781 in ten volumes octavo, both of which works 

 for their excellence in the time of publication, soon after the appearance of 

 Limit's works, and for their aid in the diffusion of scientific knowledge deserve 

 much from the scientist. In choosing a nomenclature it is better to take from 

 such works the binomials correctly formed and applied than to accept them years 

 later from writers inspired by the same books. The "Schauplatz" referred to 

 above is anonymous, it is true, but it gives the authorities for its generic and 

 specific names and thus its citations amount to republication after 1758 by the 

 original authors, previous as the first publication may have been. With due 

 regard to the more generally accepted rules of priority and publication since 

 1757, the generic name of an animal applied in 1758 or later and accompanied 

 by a pertinent diagnosis or by a named characterized and recognizable species 

 is used in these pages without question of its author's standing as a binomialist. 

 This limits attention to the merits of the diagnosis and prevents the intermina- 

 ble discussions of those of its author. 



The following notes will explain certain adoptions and changes. 



Chondropterygii. — This term is used by Linne, 1735, Artedi, 1738, Gronow, 

 1754-63, Gmelin, 1789, and Walbaum, 1792; the names for its subdivisions 

 Chismopnea and Plagiostomia and for the subdivisions of the Plagiostomia, 

 the Antacea and the Platosomia, are from Rafinesque, 1815, as is set forth 

 at greater length in the publication on the Chimaeroids, Garman, 1904, 

 Bull. M. C. Z., 41, p. 269. 



Hexeptranchidae. — Heptranchias and Hexanchus are generic names given 

 by Rafinesque in 1810 to sharks having seven and six pairs of gill openings 

 respectively. These genera were thrown together by Cuvier, in 1817 and 

 1829, in his genus Notidanus, from which authors have formed the name 

 Notidanidae. Notidanus being reduced to the synonymy the name Notida- 

 nidae loses its pertinence. A later family name, Hexanchidae, used by some 

 authors is not well adapted for inclusion of a seven-gilled genus, and simi- 

 larly Heptranchiidae should not include a six-gilled genus. To obviate 

 these objections a portion of the name of each genus is used to form the 

 word Hexeptranchidae. 



