4 THE PLAGIOSTOMIA. 



Galeus. — "Cagnot bleu, Galeus glaucus" appears, with a description, on page 

 371 of the first volume of Valmont's work. Adopting this name for the 

 genus, the type is Squalus glaucus Linne, 1758. This anticipates the use of 

 Galeus by Rafinesque, 1810, for the genus later named Pristiurus by Bona- 

 parte, 1832, or that by Cuvier, 1817, for species which had no generic name 

 properly their own before that by Gill, 1864, Eugaleus. 



Carcharinus. — Under this name, as a subgenus of Squalus Blainville, 1816, 

 placed fourteen species. The first of these C. commersonii was known from 

 a recognizable figure by Lacepede, 1798, of Le Squale Requin, 1, pi. 8, f. 2, 

 which, with part of the description, leaves no doubt of the generic characters 

 of the young specimen figured. This figure served as the original of Blain- 

 ville's species C. commersonii, as asserted by him on page 90 of the Fauna 

 Frangaise, Poissons. 



Cestracion. — This genus is from Klein, 1776, as reprinted in the Schauplatz, 3, 

 p. 524, with the type species Squalus zygaena Linne, 1758. Walbaum, 

 1792, Art. Gen. Pise, p. 580, also gives the genus from Klein including the 

 species Squalus zigaena and S. tiburo of Linne. 



Centracion. — This name was given to one of the Port Jackson Sharks by Gray, 

 1831, in the first number of his Zoological miscellany, p. 5. The entry is 

 ''Zebra Centracion. Centracion zebra n. s."; it is followed by the descrip- 

 tion of a species accepted as valid by authorities generally. Heretofore 

 it has been taken for granted that Centracion was a mistake or a misprint 

 for Cestracion, the latter as applied by Cuvier, 1817, to the Port Jackson 

 Shark. Cuvier did not, as usual, give a derivation of his generic name; 

 and there is a possibility that Cestracion is an error, since neither Kecrrpa, 

 a hammer or pickaxe, nor KeaTpov^ an instrument for engraving, is espe- 

 cially pertinent. It may have been that Gray intended substituting 

 Centracion for Cestracion, the latter having been used in the Schauplatz, 

 1776, and by Walbaum, 1792, irom Klein, for the Hammer-Head Sharks. 

 However this may have been, the question that concerns us is whether it is 

 better to conjecture a reason for the existence of Centracion or to accept 

 the fact, and use the word if available. The latter alternative is preferred. 

 The word does not appear to have been preoccupied; it is sufficiently 

 correct in form, is better in signification than Cestracion, and it is accom- 

 panied by the description of a firmly established species. In all respects it 

 compares favorably with any one of a number of generic names proposed 

 by the author of Centracion. Cestracion was derived from Kearpa and a/cis; 



