NOTES. 287 



One of these objections relates to the occurrence of cephalopodous 

 mollusca, which, generally speaking, are the most highly organized 

 class of invertebrates, at the first or lowest point in the rock series 

 where distinct fossils are found. The answer is (1.) that, in a 

 right view of the genealogies of the animal kingdom, the only 

 predecessors of the cephalopoda possessing hard parts are certain 

 pteropodous families, whose shells are almost too slight to have had 

 a chance of being preserved; (2.) there is a lower aqueous forma- 

 tion which may have contained remains of lower families of animals, 

 but which has been acknowledged!)- so affected by the agency of 

 heat, that any fossils which it ever bore must have been obliterated ; 

 (3.) the first cephalopoda are of low families in their class, and 

 higher genera come afterwards. See, on these points, the section on 

 the Silurian Era, and that regarding the Affinities and Geographical 

 Distribution of Animals. 



The second great objection rests upon certain peculiarities of the 

 cartilaginous order of fishes, those to which the earliest of the class 

 belonged. While existing specimens of the Cartilagines reach lower 

 down in the scale of organization than the osseous fishes, and while 

 their imperfect vertebral structure, heterocercal tails, and other pecu- 

 liarities, indicate a general inferiority, some of them present characters 

 in the nervous and reproductive systems, which the osseous fishes 

 do not possess. A few are viviparous, and manifest an affection for 

 their offspring. On these partial grounds, an assumption has been 

 built that the fishes commence with the highest forms ! The occur- 

 rence of cestraceons in the Upper Silurians is particularly insisted 

 upon as evidence for this conclusion. In reality, the few traits of 

 superiority in the cartilaginous order, even if general to it, which 

 they are not, are light in the scale, against the truly general infe- 

 riority. It is well known that no family of the animal kingdom is 

 equally high in all points of structure and endowment, and that 

 many forms, generally humble, have characteristics of a compara- 

 tively elevated kind. There are features of even the human organiza- 

 tion which would place our race below some of the inferior animals, 

 if these were to be made an exclusive criterion. The partial supe- 

 riority possessed by certain cartilaginous genera seems partly to 

 relate to their place in creation as destructives : they have a well- 

 developed nervous system to enable them to conquer their prey (see 

 Explanations, pp. 49 56). That the nervous system determines 

 the character of the reproductive system is an admitted law in 

 physiology (see Owen, Philosophical Transactions, 1834, p. 359). 

 To find, then, some of these cartilagines exhibiting a generative 

 system superior to other fishes, is no true difficulty in our course. 

 On the very same ground, the star fishes (radiata), where the sexes 

 are in different individuals, are superior to the annelides (articulata), 

 which present " an androgynous combination of simple ovaria and 

 testes ;" yet no one would think of describing the radiata generally 

 as superior to the articulata. Or the polypes might be said to be 

 superior to the star-fishes, because in some of them " the digestive 



