CONSIDERATIONS. 281 



The Mollusca, on the contrary, exhibit characters totally at 

 variance with those we have just pointed out ; on the one 

 hand, their body no longer presents that perfect parity of the 

 two lateral halves, neither is it in the least degree articulated ; 

 on the other, the nervous system is not longitudinal, its situa- 

 tion is not so constant, and its mass is less considerable. The 

 muscular system is in general much less perfect than in the 

 Annulosa ; and, taken in detail, the muscles are less distinct, 

 and only form, in the greater part of the body, a mass of 

 fibres, so interlaced that it is impossible to separate them ; thus 

 conducting us to the Entozoa, of which the body is only a 

 continuous parenchyma, without any distinct muscles. 



The character which eminently distinguishes the Mollusca 

 from the two other divisions is, that in these the organs of 

 animal — in the Mollusca those of vegetable, life — are the 

 most predominant ; whence the latter are totally devoid of that 

 industry, and we may even say intelligence, which insects pos- 

 sess in a degree far superior to all other invertebrated animals. 



Lastly, there exists a more natural passage from the Verte- 

 brata to the Annulosa than to the Mollusca; but this con- 

 nexion is by the lowest in the scale of organization of each of 

 these groups. The Vertebrata having reached the most 

 simple form compatible with their mode of organization, nature 

 has commenced from that point a new group, that of the Annu- 

 losa, by introducing successively a new series of organs, 

 altogether different from those which she has abandoned, and 

 considerably modifying those she has retained. This point is, 

 in the Ferlebrata, the genus Amnioccetes, and perhaps also 

 the genus Myxine; and in the Annulosa, the genera Gordius 

 and Hirudo. On both hands these animals are found placed 

 at the lowest point of the descending scale, formed by each of 

 these two series; and, compared with each other, these two 

 genera of fishes and the abranchial Annelida offer some 

 remarkable resemblances in the few organs which they possess. 



Here let me pause a moment, and consider our author's 

 views of arrangement, more especially as relates to insects. 

 Let any one inspect the following table, and compare it with the 

 septenary system lately proposed by my friend, Mr. Newman.* 



* A sketch of the position of Mr. Newman's classes is given by another con- 

 tributor, at p. 229.— Ed. 



NO. III. VOL. I. O O 



