1910.] AND INVERTEBRATES OF ST. HELENA. 107 



regard to sex it is obvious that there are not three sexes, and 

 although I cannot say that I examined males and females of each 

 form, I certainly saw specimens of different forms which were of the 

 same sex, and came to the conclusion that sex had nothing to do 

 with the matter. Moreover, sexual dimorphism is not known 

 in the family. 



All recent writers seem to have ignored the species albacora 

 and obesus of Lowe. Dresslar and Fesler give Thynnus albacora 

 Lowe as a synonym of Thynnus alalonga, although in their 

 diagnosis they state that the dorsals and anals are of height equal to 

 the length of the second dorsal ; whereas Lowe specially mentions 

 the great height of the second dorsal and anal, which in large 

 specimens are nearly three times as high as the length of the 

 base of the second dorsal. 



The three species of Cuvier and Valenciennes — Thynnus 

 balteatus, T. pacificus, and T. argentivittatus — are regarded by 

 Dresslar and Fesler as synonyms of alalonga, but to me the}' - seem 

 to be insufficiently characterized, and balteatus is described only 

 from a drawing. I therefore omit them from the synonymy. 



As in many other cases, the application of the rules of nomen- 

 clature has caused great diversity of opinion on the question of 

 the generic names of Scombridse in general and of the tunnies in 

 particular ; scarcely two writers can be found to agree on the 

 subject. Thynnus, the specific name of Linnaeus, was made the 

 generic name by Cuvier ; and Lowe, as mentioned above, calls 

 the three species here considered T. alalonga, T. albacora, and 

 T. obesus. In the ' Regne Animal,' 1817, Cuvier used the name 

 Orcynus for the species alalonga, and this has been adopted by 

 several writers. The American writers Dresslar and Fesler have 

 discovered that both these names are preoccupied, Thynnus 

 having been used by Fabricius for a genus of butterflies, and 

 Orcynus by Rafinesque in 1815 for the Scombroides of Lacepede. 

 They therefore adopt the name Albacora, proposed by Jordan in 

 1889. As the names Thynnus and Orcynus have been applied to 

 the well known tunny from the times of the ancients, it seems 

 to me absurd on pedantic grounds of priority to allow them to be 

 confined to a genus of butterflies or another genus of fishes, and 

 I propose to follow Lowe in using the name Thynnus for these 

 species, placing them in the same genus as the Common Tunny, 

 which therefore becomes Thynnus thynnus. The generic cha- 

 racters are : — Body entirely covered with scales, which are larger 

 in the anterior part and sometimes form a distinct corselet ; vomer 

 and palatines with villiform or minute teeth ; teeth in jaws slender, 

 subcorneal ; body robust, not compressed. 



It appears that only one of these three species, namely Thynnus 

 alalonga, occurs to the north of Madeira. The others have never- 

 been identified on the coasts of Europe or North America, and only 

 alalonga is mentioned in the King of Portugal's " Pesca do atum 

 no Algarve en 1898," published in 1899 as the first memoir of 

 ' Resultados das Investigacoes scientificas feitas a bordo do Yacht 



