10 Dr. C F. Liitken on the Changes of Form in Fishes 



the bonito {T. pelamys) and T. thunnina, a species from 

 which T. affinis probably does not differ; and I reserve that 

 of Orcynus for " the large tunnies " — that is to say, the true 

 tunny [0. thynnus) and the ^'germon" or albacore of our 

 sailors ( 0. germo) , a species which is rendered recognizable 

 by the long pectorals and the prolongation in a sabre-like 

 form, in the adult, of the second dorsal and the anal. These 

 four species are all extremely cosmopolitan in their geogra- 

 phical distribution (which also seems to be the case, although 

 in a less degree, with Auxis) ; those of the whole group 

 which have the pelagic character most strongly marked are 

 Orcynus germo and Thynnus pelamys. A critical revision of 

 the species described under other names, a revision founded 

 on the comparison of individuals of different sizes belonging 

 to several of the four principal types above mentioned, has 

 convinced me, or at least rendered it very probable, that 

 most of these species must be eliminated, as resting only upon 

 quite secondary differences, to a great extent arising from age. 

 Thus T, hrachypterus is without the least doubt nothing 

 but a young form of Orcynus thynnus, and T. brevipeiinis a 

 still younger form of the same, or rather a corresponding form 

 of T. thunnina. I must here remark that the want of the 

 swimming-bladder, which is generally attributed to the true 

 tunny, is apparently founded on a mistake ; it is described 

 in detail by M. Malm in his ' Fauna of Bohuslan.' Further, 

 I have no hesitation in identifying Thynnus secundodor satis, 

 Storer, and E. orientalis from Japan with 0. thynnus; Thyn- 

 nus coretta is a form intermediate between Orcynus thynnus 

 and T. hrachypterus, and may consequently also be struck 

 out of the catalogue. With Orcynus germo ( pacijicus) , again, 

 I identify T. alalonga, alhacora, argentivittatus, balteatus, 

 sibi, and macropterus, which inhabit different parts of the 

 great ocean ; but I hesitate about including in this suppression 

 of species 0. subulatus, Poey, of Cuba^ and 0. pacijicus, Cooler, 

 of California, — the former on account of its pectorals, which 

 are singularly short for an albacore ; the latter, on the con- 

 trary, on account of extraordinary prolongation of these same 

 fins. At any rate the characters ascribed to these two forms of 

 albacores require confirmation in this respect. As to the generic 

 separation of the albacores, with long pectorals, from the true 

 tunnies, with shorter pectorals, there seems at present no 

 reason for making it. From these forms, which I unite under 

 the generic denomination ol Orcyyius, the "small tunnies" 

 [Thynmis s. str. m.) differ: — 1, by the absence of teeth on 

 the vomer, a character which has hitherto passed entirely un- 

 noticed, but to which, in the group of the Thynnid^, generic 



