380 Proceedings of the British Association. 



An account of excursions in the neighbourhood of Quito, and 

 towards the summits of Chimborazo and Pichincha, by Colonel 

 Hall. 



Professor Agassiz next delivered some very interesting observa- 

 tions upon the different species of the Genus Salmo which frequent 

 the various rivers and lakes of Europe, of which the following is 

 an abstract : — 



The genus Salmo, as it has been established by Linnseus and 

 Artedi, or, I ought rather to say, by Rondeletius, has supplied 

 Cuvier with the type of a peculiar family, in which he has re- 

 tained the generic characters of Linnseus, viz. one dorsal fin with 

 soft rays, and a second one, which is rudimental and only adi- 

 pose. Cuvier places this family in his order Malacopterygii Abdo- 

 minaleSf between the Siluridce and the ClupecB; and he subdivides it, 

 on just grounds, into a great number of generic sections, which 

 comprehend a vast variety of exotic species. In my work on the 

 fishes of Brazil, I have added several new kinds to those which 

 Cuvier established ; and am of opinion that, in the natural classi- 

 fication, it is now absolutely necessary to unite the family of the 

 Clupese to that of the Salmones, since the only difference we find 

 between them consists in the presence or absence of an adipose 

 fin ; an organ assuredly too insignificant to constitute the distinctive 

 character betwixt two families, and the less so, as there are some 

 genera of the family which possess it, whilst in others it is completely 

 awanting, as for example, in the Siluridse. We may with equal 

 truth affirm, that all the real Salmones of Cuvier have not this adi- 

 pose fin, for in many species of the genera Serrasalmus, Myletes, &c. 

 it is composed of rays which are truly osseous. 



Restricted to the limits which Cuvier has assigned to it, the 

 genus Salmo comprehends all the species of which the body is 

 somewhat lengthened, the mouth large, and supplied with teeth, 

 which are conical, pointed and formidable, implanted into all the 

 bones of the mouth, that is to say, into the interior maxillary bones, 

 both superior and inferior, into the vomer and palate bones, into 

 the tongue itself, and into the branchial arches. The margin of 

 the upper jaw is formed by the interior and superior maxillary 

 bones, and constitutes only a single continuous arch, as in the higher 

 classes of animals ; a conformation which in the class of fishes is 

 found only in the Clupeae. It is also singular that the number of 

 branchial rays is seldom exactly the same on the opposite sides 

 of the head, the number varying from ten to twelve. The pecto- 



